Endoluminal device and method

ABSTRACT

An endoluminal device can be configured for precise positioning during deployment within a vessel. The endoluminal device can be a tack, stent, vascular implant or other type of implant. The endoluminal device can have circumferential member with an undulating configuration having multiple inward and outward apexes and struts extending therebetween. Two of the struts can be used to establish a foot for the precise positioning of the device during deployment. A method of placing the endoluminal device can include withdrawing an outer sheath such that a portion of the endoluminal device is expanded prior to the rest of the endoluminal device.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation of U.S. patent application Ser. No.15/921,541, filed on Mar. 14, 2018 and issued as U.S. Pat. No.10,166,127, which Ser. No. 15/921,541 is a continuation of U.S. patentapplication Ser. No. 15/654,586, filed on Jul. 19, 2017 and issued asU.S. Pat. No. 10,117,762, which Ser. No. 15/654,586 is a divisional ofU.S. patent application Ser. No. 13/749,643, filed on Jan. 24, 2013 andissued as U.S. Pat. No. 9,730,818, which Ser. No. 13/749,643 claimspriority benefit of U.S. Provisional Patent App. No. 61/590,775, filedon Jan. 25, 2012, and which Ser. No. 13/749,643 is acontinuation-in-part of U.S. patent application Ser. No. 13/179,458,filed on Jul. 8, 2011 and issued as U.S. Pat. No. 10,022,250, which Ser.No. 13/179,458 claims priority benefit of U.S. Provisional Patent App.No. 61/362,650, filed on Jul. 8, 2010, and which Ser. No. 13/179,458 isa continuation-in-part of U.S. patent application Ser. No. 13/153,257,filed on Jun. 3, 2011 and issued as U.S. Pat. No. 9,375,327, and whichSer. No. 13/179,458 is a continuation-in-part of U.S. patent applicationSer. No. 13/118,388, filed on May 28, 2011, which Ser. No. 13/118,388claims priority benefit of U.S. Provisional Patent App. No. 61/349,836,filed May 29, 2010. All of the above applications are incorporated byreference herein and made a part of this specification.

BACKGROUND OF THE INVENTION Field of the Invention

This invention relates to treatment of atherosclerotic occlusive diseaseby intravascular procedures for pushing and holding plaque accumulatedon the blood vessel walls out of the way for reopened blood flow.

Atherosclerotic occlusive disease is the primary cause of stroke, heartattack, limb loss, and death in the US and the industrialized world.Atherosclerotic plaque forms a hard layer along the wall of an arteryand is comprised of calcium, cholesterol, compacted thrombus andcellular debris. As the atherosclerotic disease progresses, the bloodsupply intended to pass through a specific blood vessel is diminished oreven prevented by the occlusive process. One of the most widely utilizedmethods of treating clinically significant atherosclerotic plaque isballoon angioplasty.

Balloon angioplasty is an accepted method of opening blocked or narrowedblood vessels in every vascular bed in the body. Balloon angioplasty isperformed with a balloon angioplasty catheter. The balloon angioplastycatheter consists of a cigar shaped, cylindrical balloon attached to acatheter. The balloon angioplasty catheter is placed into the arteryfrom a remote access site that is created either percutaneously orthrough open exposure of the artery. The catheter is passed along theinside of the blood vessel over a wire that guides the way of thecatheter. The portion of the catheter with the balloon attached isplaced at the location of the atherosclerotic plaque that requirestreatment. The balloon is inflated to a size that is consistent with theoriginal diameter of the artery prior to developing occlusive disease.When the balloon is inflated, the plaque is broken. Cleavage planes formwithin the plaque, permitting the plaque to expand in diameter with theexpanding balloon. Frequently, a segment of the plaque is more resistantto dilatation than the remainder of the plaque. When this occurs,greater pressure pumped into the balloon results in full dilatation ofthe balloon to its intended size. The balloon is deflated and removedand the artery segment is reexamined. The process of balloon angioplastyis one of uncontrolled plaque disruption. The lumen of the blood vesselat the site of treatment is usually somewhat larger, but not always andnot reliably.

Some of the cleavage planes created by fracture of the plaque withballoon angioplasty can form a dissection. A dissection occurs when aportion of the plaque is lifted away from the artery, is not fullyadherent to the artery and may be mobile or loose. The plaque that hasbeen disrupted by dissection protrudes into the flow stream. If theplaque lifts completely in the direction of blood flow, it may impedeflow or cause acute occlusion of the blood vessel. There is evidencethat dissection after balloon angioplasty must be treated to preventocclusion and to resolve residual stenosis. There is also evidence thatin some circumstances, it is better to place a metal retainingstructure, such as stent to hold open the artery after angioplasty andforce the dissected material back against the wall of the blood vesselto create an adequate lumen for blood flow.

The clinical management of dissection after balloon angioplasty iscurrently performed primarily with stents. As illustrated in FIG. 1, astent 3 is a tube having a diameter that is sized to the artery 7. Astent is placed into the artery at the location of a dissection to forcethe dissection flap against the inner wall of the blood vessel. Stentsare usually made of metal alloys. They have varying degrees offlexibility, visibility, and different placement techniques. Stents areplaced in every vascular bed in the body. The development of stents hassignificantly changed the approach to minimally invasive treatment ofvascular disease, making it safer and in many cases more durable. Theincidence of acute occlusion after balloon angioplasty has decreasedsignificantly with stents.

However, stents have significant disadvantages and much research anddevelopment is being done to address these issues. Stents induce repeatnarrowing of the treated blood vessel (recurrent stenosis). Recurrentstenosis is the “Achilles heel” of stenting. Depending on the locationand the size of the artery, in-growth of intimal hyperplastic tissuefrom the vessel wall in between struts or through openings in the stentmay occur and cause failure of the vascular reconstruction by narrowingor occlusion of the stent. This may occur any time after stentplacement. In many cases, the stent itself seems to incite local vesselwall reaction that causes stenosis, even in the segment of the stentthat was placed over artery segments that were not particularly narrowedor diseased during the original stent procedure. This reaction of theblood vessel to the presence of the stent is likely due to thescaffolding effect of the stent. This reaction of recurrent stenosis ortissue in growth of the blood vessel is in response to the stent. Thisactivity shows that the extensive use of metal and vessel coverage inthe artery as happens with stenting is contributing to the narrowing.The recurrent stenosis is a problem because it causes failure of thestent and there is no effective treatment. Existing treatment methodsthat have been used for this problem include; repeat angioplasty,cutting balloon angioplasty, cryoplasty, atherectomy, and even repeatstenting. None of these methods have a high degree of long-term success.

Stents may also fracture due to material stress. Stent fracture mayoccur with chronic material stress and is associated with thedevelopment of recurrent stenosis at the site of stent fracture. This isa relatively new finding and it may require specialized stent designsfor each application in each vascular bed. Structural integrity ofstents remains a current issue for their use. Arteries that areparticularly mobile, such as the lower extremity arteries and thecarotid arteries, are of particular concern. The integrity of the entirestent is tested any time the vessel bends or is compressed anywherealong the stented segment. One reason why stent fractures may occur isbecause a longer segment of the artery has been treated than isnecessary. The scaffolding effect of the stent affects the overallmechanical behavior of the artery, making the artery less flexible.Available stenting materials have limited bending cycles and are proneto failure at repeated high frequency bending sites.

Many artery segments are stented even when they do not require it,thereby exacerbating the disadvantages of stents. There are severalreasons for this. Many cases require more than one stent to be placedand often several are needed. Much of the stent length is often placedover artery segments that do not need stenting and are merely adjoiningan area of dissection or disease. Stents that are adjusted to theprecise length of the lesion are not available. When one attempts toplace multiple stents and in the segments most in need of stenting, thecost is prohibitive since installation and material is required perstent. The time it takes to do this also adds to the cost and risk ofthe procedure. The more length of artery that receives a stent that itdoes not need, the more stiffness is conferred to the artery, and themore scaffolding affect occurs. This may also help to incite thearterial reaction to the stent that causes recurrent stenosis.

SUMMARY OF THE INVENTION

There exists a continuing need to develop new and improved devices toassist in the treatment of vascular disease, including atheroscleroticocclusive disease, among other conditions, and such as for the purposesoutlined above.

In some embodiments, a self-expanding endoluminal device can beconfigured for precise positioning during deployment within a vessel.The endoluminal device has a longitudinal axis extending between adistal end and a proximal end, the endoluminal device configured forradial compression and expansion. The endoluminal device can comprise afirst undulating ring disposed at the distal end and a proximal portion.The first undulating ring can extend circumferentially around thelongitudinal axis, the first undulating ring comprising a plurality ofstruts, a plurality of inward apexes and a plurality of outward apexes,wherein at least two struts connect at one of the apexes, the outwardapexes being distal of the inward apexes. The proximal portion can beconnected to the inward apexes. The endoluminal device is configured fordelivery such that the first undulating ring can at least partiallyexpand while the proximal portion remains compressed. In this position,a first strut of the plurality of struts extends at an angle radiallyoutward from the longitudinal axis, the first strut connected to thecompressed proximal portion; and a second strut and a third strut of theplurality of struts are connected to the first strut and extend parallelto the longitudinal axis, the second and third struts forming a foot andthe endoluminal device comprising a plurality of such feet configured toextend parallel to the longitudinal axis when the endoluminal device isin this partially expanded position, the feet positionedcircumferentially around the longitudinal axis and configured toprecisely position and orientate the endoluminal device within thevessel upon further expansion and deployment of the endoluminal devicewithin the vessel.

The endoluminal device can be a tack, stent, vascular implant or othertype of implant.

According to some embodiments, an endoluminal device can comprise afirst circumferential member disposed at a distal end of the endoluminaldevice, the first circumferential member having a first outward apexdisposed between first and second struts, a second outward apex disposedbetween third and forth struts, a first inward apex disposed between thesecond and third struts, and a second inward apex disposed adjacent tothe fourth strut; a second circumferential member disposed at theproximal end of the endoluminal device; and a bridge member having afirst end coupled with the second inward apex and a second end coupledwith the second circumferential member, the bridge member having aplaque anchor disposed at or adjacent a central zone of the bridgemember. The first inward apex can extend a first axial distance from acentral zone of the bridge member and the second inward apex extends asecond axial distance from the central zone of the bridge member, thefirst distance being greater than the second distance, such that thesecond and third struts form a foot that can extend outward from thesecond circumferential member when the endoluminal device is in apartially expanded position, the foot being substantially parallel to alongitudinal axis of the endoluminal device.

In some embodiments, an endoluminal device can comprise a firstcircumferential member disposed at a distal end of the endoluminaldevice, the first circumferential member having a first outward apexdisposed between first and second struts, a second outward apex disposedbetween third and forth struts, a first inward apex disposed between thesecond and third struts, and a second inward apex disposed adjacent tothe fourth strut; and a second circumferential member disposed at theproximal end of the endoluminal device. The first inward apex ispositioned distally from the second inward apex, such that the secondand third struts form a foot that can extend outward from the secondcircumferential member when the endoluminal device is in a partiallyexpanded position, the foot being substantially parallel to alongitudinal axis of the endoluminal device.

An endoluminal device can include first and second circumferentialmembers disposed at either end of the endoluminal device. The firstcircumferential member can have an undulating configuration havingmultiple inward and outward apexes and struts extending therebetween. Amethod of placing the endoluminal device can include withdrawing anouter sheath such that a portion of the endoluminal device is expandedprior to the rest of the endoluminal device.

An endoluminal device can include proximal and distal circumferentialmembers. The proximal circumferential member can be disposed at aproximal end of the endoluminal device. The distal circumferentialmember can be disposed at a distal end of the endoluminal device. Insome embodiments, the distal circumferential member is the distal mostaspect of the endoluminal device and the proximal circumferential memberis the proximal most aspect of the endoluminal device. The proximal anddistal circumferential members can be connected by bridge members. Thebridge members can include one or more anchors configured to engage theplaque and/or the blood vessel wall.

In some embodiments, a catheter based endoluminal device can include aproximal circumferential member, a distal circumferential member, and aplurality of bridge members. The proximal circumferential member can bedisposed at a proximal end of the endoluminal device and have asinusoidal configuration with a first plurality of inward apices, afirst plurality of outward apices, a second plurality of inward apices,and a second plurality of outward apices, each of the second pluralityof inward apices spaced proximally from the first plurality of inwardapices. The distal circumferential member can be disposed at a distalend of the endoluminal device and have a sinusoidal configuration with athird plurality of inward apices, a third plurality of outward apices, afourth plurality of inward apices, and a fourth plurality of outwardapices, each of the fourth plurality of inward apices spaced distallyfrom the third plurality of inward apices. Each bridge member canconnect one apex of the first plurality of inward apices of the proximalcircumferential member to one apex of the third plurality of inwardapices of the distal circumferential member. Each apex of the fourthplurality of apices of the distal circumferential member can beunconnected to any of the plurality of bridge members or to any of thesecond plurality of apices of the proximal circumferential member.

In some embodiments, an endoluminal device can comprise a firstcircumferential member disposed at a proximal end or a distal end of theendoluminal device, a second circumferential member disposed adjacent tothe first circumferential member, and a bridge member. The firstcircumferential member can have a first outward apex disposed betweenfirst and second struts, a second outward apex disposed between thirdand forth struts, a first inward apex disposed between the second andthird struts, and a second inward apex disposed adjacent to the fourthstrut. The bridge member can have a first end coupled with the secondinward apex and a second end coupled with the second circumferentialmember. The bridge member can also have a plaque anchor disposed at oradjacent a central zone of the bridge member. The first inward apex canextend a first axial distance from the central zone of the bridge memberand the second inward apex extends a second axial distance from thecentral zone of the bridge member, the first distance being greater thanthe second distance.

In some embodiments a method of placing an endoluminal device caninclude one or more of the following steps. Providing a catheter systemincluding an elongate body having a delivery platform disposed adjacenta distal portion of the elongate body and marker band located at thedistal end of the delivery platform, the delivery platform having anendoluminal device disposed thereon and an outer sheath positioned overthe endoluminal device. Advancing the distal portion of the elongatebody through the vasculature of a patient until the marker band islocated at a treatment zone. Visualizing the marker band to confirm thelocation of the delivery platform relative to the treatment zone.Retracting the outer sheath while maintaining the position of theelongated body such that a plurality of feet of a first circumferentialmember disposed at a distal end of the endoluminal device are releasedfrom the delivery platform prior to release of the rest of theendoluminal device. The first circumferential member can comprise afirst outward apex disposed between first and second struts, a secondoutward apex disposed between third and forth struts, a first inwardapex disposed between the second and third struts, and a second inwardapex disposed adjacent to the fourth strut. The feet can comprise thefirst inward apex, the first outward apex, the second outward apex, thesecond strut and the third strut, the feet assuming a pre-fully deployedposition prior to full expansion.

BRIEF DESCRIPTION OF THE DRAWINGS

These and other features, aspects and advantages are described belowwith reference to the drawings, which are intended to illustrate but notto limit the invention. In the drawings, like reference charactersdenote corresponding features consistently throughout similarembodiments.

FIG. 1 illustrates the use of a stent installed after angioplasty asconventionally practiced in the prior art.

FIG. 2 illustrates the use of plaque tacks installed after anendolumenal procedure demonstrating advantages over the prior art.

FIG. 3 shows an embodiment of a plaque tack in end view, FIG. 3B showsit in side view, FIG. 3C shows the plaque tack in perspective, and FIG.3D shows a section of the plaque tack in a flat or rolled-out view.

FIG. 4 is a schematic representation of a distal portion of a deliverydevice that has been advanced to a treatment site expanded in the bloodvessel.

FIG. 4A illustrates the proximal end of one embodiment of a deliverydevice.

FIG. 4B is a plan view of the distal portion of the delivery deviceshown in FIG. 4.

FIG. 4C is a cross-sectional view of the distal portion of FIG. 4Bshowing a plurality of tack devices prepared for implantation.

FIG. 4D shows the deployment of two tack devices upon retraction of asheath.

FIGS. 5A and 5B show another embodiment of a plaque tack in a collapsedstate and in an expanded state, respectively.

FIG. 5C shows a detail view of a section of the plaque tack of FIG.5A-B.

FIG. 5C1 shows a variation on the embodiment of FIGS. 5A-5C having anincreased size anchor.

FIG. 5D shows a variation on the embodiment of FIGS. 5A-5C having ananchor disposed on a midline of the tack.

FIG. 5E shows a variation with struts that taper from wider at a lateraledge of a tack to narrower at a mid-section of the strut and/or fromnarrow at a mid-section of a strut to wider adjacent to a mediallocation of the tack.

FIG. 5F shows a variation of the tack with an inner apex spaced from theother inner apex.

FIG. 5G illustrates a partially expanded tack during delivery.

FIGS. 5H-5J show additional variations of the tack.

FIG. 6A is a chart comparing the expansion forces of a plaque tack to astent.

FIG. 6B illustrates the use of multiple plaque tacks which are spacedapart over the length of a treatment site as compared to a typicalstent.

FIG. 7A shows another embodiment of a plaque tack in a fully compressedstate. FIG. 7D shows the plaque tack in a fully expanded state and FIGS.7B and 7C show the plaque tack in states of expansion between the fullycompressed and expanded states.

FIG. 8 is a schematic view of the focal elevating element of a plaquetack in FIGS. 7A-D.

FIG. 9 is a schematic diagram illustrating the variables for computingthe elevated tack surface due to the use of focal elevating elements ina plaque tack device.

FIG. 10 illustrates use of a plaque tack with focal elevating elementsfor holding a plaque against a blood vessel wall.

FIGS. 11 and 12 illustrate a variant use of focal elevating elements ona plaque tack.

FIGS. 13 and 14 illustrate another variant of focal elevating elementson a plaque tack.

FIG. 15 illustrates the use of focal elevating elements to reshapeartery walls into a desired cross-sectional shape.

FIGS. 16-22 illustrate variations in forming and positioning focalelevating elements on the struts of a plaque tack.

FIGS. 23-29 illustrate a method of delivery of a plaque tack into ablood vessel.

FIGS. 30A-B show a focal elevating element engaging plaque.

FIGS. 31A-B show anchors engaging plaque.

FIG. 32A-32B show the proximal and distal end views respectively of asystem for delivering a vascular prosthesis, where a distal end of asheath of the system is disposed distally of one or more plaque tacks.

FIG. 33A-33B show the proximal and distal end views respectively of thesystem of FIGS. 32A-32B, where the sheath distal end is disposedproximally of one or more plaque tacks.

FIG. 34 shows a system for delivering a vascular prosthesis.

FIG. 35 shows a sheath that can be used to retain and to deploy one ormore tacks.

FIGS. 36-36A illustrate one embodiment of an elongate body that can haveone or more plaque tacks disposed therearound within the sheath of FIG.35.

FIGS. 36B-F show embodiments of markers on the delivery system.

FIGS. 37A-37B illustrate a variation of the delivery system in which anactively actuated member is provided to anchor the system near thetreatment zone.

FIG. 38 illustrates a variation of the delivery system in which alinkage is provided to actively actuate a member positioned near thetreatment zone.

FIGS. 39-40 illustrate delivery systems with passively expanding membersfor stabilizing a distal delivery zone.

FIG. 41 illustrates a delivery system having a friction isolation sheathto stabilize a distal delivery zone.

FIG. 42 illustrates a delivery system including a deployable packet formaintaining a spacing between adjacent prostheses.

FIG. 43 illustrates one embodiment of a deployment packet adapted tomaintaining a spacing between adjacent prostheses.

FIG. 44 illustrates a delivery system including a deployable packet formaintaining a spacing between adjacent prostheses, having a constrainingelement disposed inside the tacks.

FIG. 45 illustrates a balloon that is optimized for deploying a plaquetack to induce plaque engaging rotation in a plaque anchor.

FIG. 45A shows a balloon for deploying multiple tacks.

FIG. 46-48D illustrates a portion of a deployment system that can beused with any of the delivery systems disclosed herein.

FIG. 49 shows a shuttle deployment device.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

The subject matter of this application is directed to the improvement ofa plaque tack or staple device. The plaque tack or staple device can beused for treating atherosclerotic occlusive disease. The plaque tack canbe used to hold loose plaque against a blood vessel wall. The plaquetack can include an annular member configured to apply an expansionforce to the loose plaque.

I. Overview of Endolumenal Tack Treatment

FIG. 2 shows one embodiment of a plaque tack or staple device 5 thatincludes a thin, annular band or ring of durable, flexible material. Thetack device can be inserted into a blood vessel in a compressed stateand installed in an expanded state against the blood vessel wall using acatheter delivery mechanism at one or more specific positions of looseplaque. The plaque tack 5 can be deployed after or as part of anangioplasty procedure. The plaque tack 5 is adapted to apply anexpansion force against the plaque in the blood vessel 7 to press andhold the plaque against the blood vessel walls. The tack device can beradially outwardly expandable under a spring or other expansion force.Preferably the fully expanded diameter of the tack 5 is greater than thetransverse size of the vessel to be treated. As discussed below, thetack 5 advantageously can be deployed in a surprising large range ofblood vessel sizes.

The plaque tack 5 can include a plurality of plaque anchors 9 on itsouter annular periphery. The plaque anchors 9 can be embedded into or atleast placed in physical contact with plaque by expanding up against theplaque. In certain embodiments, the plaque anchors 9 are adapted toelevate adjacent sections of the tack 5 relative to the wall of thevessel. In at least this sense, the anchors 9 may have some of theadvantages of focal elevating elements that are discussed in SECTION IIIbelow. The anchors 9 exert a holding force on the plaque whileminimizing the amount of material surface area in contact with theplaque or blood vessel wall. As another feature, the plaque tack 5 canextend over only a small area in the axial direction of the vessel wall,in order to minimize the amount of foreign structure placed in the bloodvessel. For example, each plaque tack 5 can have an axial length L thatis only a small fraction of the axial length of a typical stent.

The plaque tack devices of the present application are designed as aminimally invasive approach to tacking loose or dissectedatherosclerotic plaque to the wall of the artery, as illustrated in FIG.2. The plaque tack may be used to treat either de novo atheroscleroticlesions or the inadequate results of balloon angioplasty. The plaquetack is designed to maintain adequate lumen in a treated artery withoutthe inherent disadvantages of vascular stents. The device may also beused to administer medications, fluid, or other treatment (“eluting”)agents into the atherosclerotic plaque or the wall of the blood vesselor into the bloodstream.

One or more plaque tacks 5 can be accurately deployed in positions alongthe length of a plaque accumulation site where specific holding forcesare needed to stabilize the site and/or hold pieces of plaque out of theway of blood flow.

FIG. 2 shows that in various plaque tack treatments, a plurality ofplaque tacks 5 can be deployed to treat locations that are axiallyspaced along the vessel 7. In this way, targeted treatments can beprovided to hold loose plaque against a vessel wall withoutover-scaffolding as discussed below. The plaque tack 5 and installationprocedure may be designed in a number of ways that share a commonmethodology of utilizing the outward force of a spring-like annular bandto enable the tack to be compressed, folded, or plied to take up asmall-diameter volume so that it can be moved into position in the bloodvessel on a sheath or catheter, then released, unfolded or unplied to anexpanded state within the blood vessel.

The plaque tack device can be delivered into the blood vessel fromendovascular insertion. SECTION IV below discusses a variety of deliverymethodologies and devices that can be used to deploy plaque tacks. Thedelivery device for the different embodiments can be the same, or can bedifferent with features specifically designed to deliver the specifictack. The plaque tack and installation procedure may be designed in anumber of ways that share a common methodology of utilizing an expansionforce of the delivery mechanism (such as balloon expansion) and/or theexpansion force of a compressible annular band to enable the tack to bemoved into position in the blood vessel, then released, unfolded orunplied to an expanded state within the blood vessel.

II. Further Embodiments of Endoluminal Staples

Variations of the plaque tack 5 can have a mesh-like configuration andcan be arranged with one or more circumferential members formed withdiscrete struts, such as in open and closed cell constructions, amongother designs.

A. Plaque Tack with Metallic Mesh Construction

An embodiment of a plaque tack 10 in the form of a metallic meshconstruction is illustrated in FIGS. 3-3D. The plaque tack 10 is shownhaving a closed cell construction with an annular band 10 a formed ofinterleaved mesh, and radially outwardly extending projections 10 b. Theplaque tack 10 may be laser cut or etched out of a metal tube form ormade of thin metal wire which is looped and interleaved in a mesh thatis welded, soldered, looped and/or linked together into the desired meshshape as can be seen in FIGS. 3C-D. The projections 10 b can project outfrom the annular band 10 a. The projections 10 b can be on an outersurface of the tack and can contact and/or embed into the wall of ablood vessel.

The annular band of the plaque tack 10 can have a dimension in the axialdirection of the vessel walls (sometimes referred to herein as length)that is about equal to or less than its expanded diameter, in order tominimize the emplacement of foreign scaffolding structure in the bloodvessel. Expanded diameter means final diameter in an unconstrainedexpansion. One or more tacks can be applied only in positions along thelength of a plaque accumulation site where specific holding forces areneeded to stabilize the site and/or hold pieces of plaque out of the wayof blood flow.

The mesh pattern can be designed so that the plaque tack 10 can becompressed radially inward to a smaller-volume size. This can allow theplaque tack 10 to be loaded onto or within a catheter delivery device tobe inserted into the blood vessel. For example, the tack 10 can have anoverall circular shape with bends, such as inner V bends, that allow itto be folded in zig-zag fashion to a compressed smaller-volume form forloading in a delivery catheter, such as a deployment tube.

At the desired position in the blood vessel, the compressed plaque tack10 is released from the delivery catheter. The mesh combined with anannular, ring shape can allow the plaque tack 10 to spring back to itsexpanded shape. Alternatively, the tack 10 can be expanded by anotherdevice, such as by a balloon. FIG. 3C shows the plaque tack 10 at restin its fully expanded state and FIG. 3D shows a detail of a section ofthe metallic mesh.

FIGS. 4-4D show that one or more plaque tacks 10 can be positioned in apatient's vasculature at a treatment site by a delivery device 11 withan outer sheath 13 and thereafter expanded. Enhancements of the deliverydevice 11 are discussed below in SECTION IV. The tack 10 can be expandedin any suitable way, such as by being configured to self-expand or to beballoon expanded. In the illustrated embodiment, a plurality ofself-expanding tacks 10 (or variants, such as tack 10′ or tack 10″) isdisposed inside the sheath 13. The delivery device 11 includes anelongate body 11A that is disposed at least partially within the sheath13. The delivery device 11 also includes a dilating structure 11B thatatraumatically displaces tissue and helps to guide the delivery device11 through the vasculature. The body 11A can be configured with a lumen11C extending therethrough for receipt and slideable advancement of aguidewire 40 therein. In the illustrated embodiment, the sheath 13 andthe dilating structure 11B meet to provide a smooth outer surface to thedelivery device 11, e.g. having the same outside diameter where theymeet. The body 11A can be configured with a plurality of annularrecesses 11D in which tacks 10, 10′, 10″ can be disposed. The annularrecesses 11D can be defined between one or more shoulders 11E thatprevent proximal or distal slippage of the tacks along the elongate body11A. The recesses 11D could be eliminated by providing another structurefor axially fixing the tacks 10, 10′, 10″ along the elongate body 10A.

FIGS. 4A and 4D show a proximal end of the device 11 and a manner ofdeploying the tacks 10, 10′, 10″. In particular, the proximal end of thedevice 11 includes a handle 11F and an actuator 11G. The actuator 11G iscoupled with a proximal end of the sheath 13 such that proximal anddistal movements of the actuator 11G cause proximal and distal movementof the sheath 13. FIG. 4A illustrates a distal positioning of theactuator 11G which corresponds to a forward position of the sheath 13relative to the elongate body 11A and the recesses 11D. In this positionthe recesses 11D and the tacks 10, 10′, 10″ are covered by the sheath.Movement of the actuator 11G proximally relative to the handle 11Fcauses the sheath 13 to move proximally, e.g., to the position of FIG.4D. In this position, the distal most two tacks 10, 10′, 10″ areuncovered and are permitted to self-expand in the manner discussedherein.

Returning now to FIGS. 3-3B, the projections 10 b on the surface of thetack 10 can act as anchors or elevating elements to embed into or pressagainst the plaque. An array of anchors or elevating elements can beused for linking the annular band of the tack with the plaque mass orblood vessel wall. The projections 10 b can be made of a sufficientlyrigid material to sustain a locking or engaging relationship with theblood vessel tissue and/or to pierce or engage the plaque and maintainthe locking or engaging relationship therewith. The projections 10 b mayproject at an angle of 90 degrees to the tangent of the annular band, oran acute angle may also be used.

The plaque tack may be made of a material such as a corrosion-resistantmetal, polymer, composite or other durable, flexible material. Apreferred material is a metal having “shape memory” (such as Nitinol).In some embodiments, a tack may have an axial length of about 0.1 to 6mm, an expanded diameter of about 1 to 10 mm, and an anchor height from0.01 to 5 mm. In general, the annular band of the plaque tack has alength in the axial direction of the vessel walls that is about equal toor less than its diameter, in order to minimize the amount of foreignstructure to be emplaced in the blood vessel. The annular band can havea ratio of axial length to diameter as low as 1/100.

B. Plaque Tack with Open Cell Construction

FIGS. 5A-5C illustrate that in certain embodiments, a plaque tack 10′can be configured with an open cell structure. The plaque tack 10′ caninclude one or more circumferential members that have undulating, e.g.sinusoidal, configurations and that are spaced apart in the axialdirection. The circumferential members can be coupled together at one ormore circumferentially spaced locations by axially extending members,sometimes referred to herein as bridge members. These embodiments areexpandable over a wide range of diameters and, as discussed below, canbe deployed in a variety of different vessels.

The plaque tack 10′ can have features similar to those described abovewith respect to the plaque tack 10. For example, the plaque tack 10′ mayalso be laser cut or etched out of a metal tube form. Similarly, theplaque tack 10′ may be made of a material such as a corrosion-resistantmetal (e.g., certain coated or uncoated stainless steel orcobalt-chromium alloys), polymer, composite or other durable, flexiblematerial. A preferred material is a metal having “shape memory” (such asNitinol).

FIGS. 5A-B show the overall structure of the plaque tack 10′ with anopen cell arrangement. The plaque tack 10′ is shown having twocircumferential members 12, which can be rings formed by a plurality ofzig-zag struts, joined by bridges 14 that extend between the rings 12.The rings and bridges define a column of bounded cells 16 along an outersurface of the tack. The outer surface extends about an outer periphery,e.g., an outer circumference of the tack 10′. The boundary of each ofthe cells 16 is made up of a number of members or struts. As shown, thesecond ring is a mirror image of the first ring, though the first andsecond rings may be circumferential members with differentconfigurations. Also, the bridges 14 can be symmetrical across atransverse plane extending through the axial mid-point thereof, thoughother configurations are also possible. The rings 12 can be consideredcoaxial, where that term is defined broadly to include two spaced apartrings, or structures, having centers of rotation or mass that aredisposed along a common axis, e.g., the central longitudinal axis of thetack 10′.

FIG. 5C is a schematic flat depiction of a portion of a tack 10′illustrating a portion of the cell 16 and a portion of a boundarythereof. The portion illustrated to the right of the midline C is onehalf of the cell 16 in one embodiment. The other half can be a mirrorimage, as shown in FIGS. 5A-B, an inverted mirror image, or some otherconfiguration. The portion of the ring 12 that is part of an individualcell 16 can define a portion that is repeated in a pattern along thering. In some embodiments, the ring 12 can have portions that arerepeated in a pattern that extends across cells, such as across 1.5cells, 2 cells, 3, cells, etc. The pattern of the rings 12 combined withother features of the tack 10′ can enable it to be circumferentiallycompressible. The difference between the compressed and expanded statescan be seen by comparing the compressed view shown in FIG. 5A and theexpanded view shown in FIG. 5B.

The cells 16 of the tack 10′ can be bounded by portions of two rings 12,which can be mirror images of each other. Thus, some embodiments can befully described by reference to only one side of the tack 10′ and of thecell 16. The ring 12, a portion of which is illustrated in FIG. 5C, hasan undulating sinusoidal pattern. The undulating pattern can have one ormore amplitudes, such as the dual amplitude configuration shown.

The rings 12 can have a plurality of struts or structural members 26,27, 28, 29. The plurality of struts can repeat about the circumferenceof the ring 12. The struts can be many different shapes and sizes. Thestruts can extend in various different configurations. In someembodiments, the plurality of struts 26, 27, 28, 29 extend betweeninward 18, 19 and outward apices 24, 25.

In some embodiments, the outward apices 24, 25 extend axially differentdistances as measured from a central zone or midline C of the tack 10′.In particular, the apex 24 can be considered a high apex and the apex 25can be considered a low apex in this regard. The inward apices 18, 19may be axially aligned, e.g., being positioned at the same axialdistance from the midline C. Thus, the outward apex 24 is disposedfarther away from the bridge and inward apices than the outward apex 25.In some embodiments, the axial length of the tack 10′ is measured fromthe top of the outward apex 24 on one side of the cell 16 to thecorresponding top of the outward apex 24 on the other side of the cell.Put another way, the first outward apex 24 extends a first axialdistance from the midline C of the tack 10′ and the second outward apex25 extends a second axial distance from the central zone C of the tack10′, the first distance being greater than the second distance. Eachside of the cell 16 as shown has one high outward apex 24 and one lowoutward apex 25.

The bridge 14 can be connected to the one or more of the inward apices18, 19. The bridge 14 can join the two rings 12 together. The bridge 14can have many different shapes and configurations. Some embodiments ofthe tack 10′ have a proximal ring and a distal ring with the bridgedisposed between and connecting them. As mentioned above, the bridge 14can be located at the central zone or midline C of the tack 10′. In FIG.5C, the word “proximal” refers to a location on the tack 10′ that wouldbe closest to vascular access site than the portion labeled “distal”.However, the tack 10′ can also be thought of as having a medial portionthat corresponds to the midline C and lateral portions extending in bothdirections therefrom. As such, the location labeled “proximal” is also amedial location and the location labeled “distal” is also a lateralposition. All of these terms may be used herein.

As shown, the bridge 14 is connected to each ring at the inward apex 18.In some embodiments, a bridge is connected to every inward apex, forminga closed cell construction. In other embodiments, the bridge 14 isconnected to every other inward apex, every third inward apex, or spacedfarther apart by as needed, forming a variety of open cellconfigurations. The number of bridges 14 can be chosen depending uponthe application. For example, six or fewer bridges 14 may be usedbetween the two rings 12 when desired for limiting neointimalhyperplasia.

One technique for enhancing the plaque holding capability of the bridges14 is to align plaque holding structures (such as the barb 9,projections 10 b, or the anchors discussed below) with a forceapplication location or direction of the ring 12. In some embodiments,at least a portion of the bridge 14 can be aligned, with one of thestruts of the ring 12. For example, where the bridge 14 connects to thering 12, whether at an inward apex or at a strut, that connectingportion of the bridge can extend therefrom in a manner that is aligned,partially or substantially aligned with a strut. FIG. 5C shows that thebridge 14 is connected to the inward apex 18 and that the connectingportion of the bridge is substantially aligned with the strut 26. In onetechnique, a plaque holding structure of the bridge 14 is disposed on aprojection of a longitudinal axis L_(A) of the strut 26. As discussedbelow, the tack 10′ has a plurality of anchors 20. The axis L_(A)intersects a portion of an anchor 20 to maximize a torque effect fromthe expanded strut 26 to the anchor 20. In the arrangement of FIG. 5C,an anchor on an opposite side of the centerline C is disposed on theprojection of the axis L_(A) and the projection of a longitudinal axisL_(A) of a mirror image strut 26 intersects the anchor 20 of the struton the same side of the centerline C as the strut 26 shown in FIG. 5C.In another technique, the projection of the strut 26 and its mirrorimage strut can be aligned with the centerline C, which is rigidlycoupled with the anchors 20. The bridge 14 also is aligned with a highamplitude sinusoidal section of the tack 10′.

A series of unique design features can be integrated into the tack 10′for various purposes as will be discussed in more detail in the sectionsbelow. For example, the tack 10′ can include one or more of anchors,markers and focal elevating elements, among other features. As discussedabove, FIG. 5C shows that the plaque tack 10′ can include a plurality of(e.g., two) anchors 20. The tack 10′ also can include a position marker22 on each bridge 14. The position markers 22 can be fluoroscopicallyopaque and in one arrangement are generally flat. As used in thiscontext, flat markers are arranged to have a planar outer face that istangential to a cylinder that extends through an outer surface of thetack 10′ or that is concentric with the outer surface but disposedradially inside the outer surface. The anchors 20 can similarly beconfigured to be tangential to a cylinder that extends through an outersurface of the tack 10′.

As another example, a series of unique design features can be integratedinto the tack 10′ for dynamic distribution of stresses within the tack10′. These design features can enable the uniform control of the tack10′ during compression, expansion, delivery, and catheter release. Thedesign features can also individually and/or collectively manage thestresses throughout the bulk of the tack, along the struts, and at theinterface of the tack and the blood vessel lumen. Better control of thedistribution of stresses within the tack has the benefit of reducingcellular response and tack fracture by limiting strut fatigue and theassociated micro-rubbing at the tack-blood vessel interface.Micro-rubbing includes a variety of small scale adverse interactionsbetween implants and patient tissue, such as abrasion or friction thatoccurs on a cellular or intercellular level between the tack and theblood vessel lumen.

A reduction in cellular response is believed to be achieved partlythrough a reduction of surface area contact between the tack and theblood vessel lumen and partly by maximizing alignment of the contactpoints or structures with the blood vessel cells' natural orientation.Thus, the tack is able to move with the blood vessel while decreasingthe micro-rubbing. Other devices, such as stents, contact the bloodvessel cells in ways that may extend across, e.g., transversely to,multiple cells increasing micro rubbing at the stent-blood vesselinterface.

1. Single Column Cell Design

One characteristic of the embodiment the tack 10′ of FIGS. 5A-C is thatit includes a single column open cell design contained between twozig-zag rings. This arrangement provides minimal (if any) scaffolding ofa vessel. In one sense, a ratio of the vessel contact area to the totaltreatment zone of the plaque tack 10′ is small. In this context, vesselcontact area is the sum of the area of outer portions of the tack 10′that may come into contact with the vessel wall. More particularly, thevessel contact area may be calculated as a summation for all of thestruts of the length of each strut times the average transversedimension (width) of the radially outer surface of each strut. If thestruts of the zig-zag rings are laser cut, the width of the radiallyouter surface of the strut may be less than that of the radially innersurface. The vessel contact area may also include the radially outersurface of the bridges 14. The total treatment zone of the plaque tack10′ can be defined with respect to the fully expanded configuration in abest fit cylinder. A best fit cylinder is one that has an innercircumference that equal to the unconstrained circumference of theplaque tack 10′. The total treatment zone has an area that is definedbetween the proximal and distal ends (or the lateral edges) of theplaque tack 10′. The total treatment zone can be calculated as thelength between the proximal and distal ends (or lateral edges) in thebest fit cylinder times the inner circumference of the best fitcylinder. In the illustrated embodiment, the length for purposes ofdetermining the total footprint can be the distance at the samecircumferential position between high outward apices of the rings 12.

In various embodiments, the ratio of the vessel contact area to totaltreatment zone is less than 50%. In some embodiments, the ratio of thevessel contact area to total treatment zone is even less, e.g., 40% orless. The ratio of the vessel contact area to total treatment zone canbe as small as 20% or less. In specific examples, the ratio of thevessel contact area to total treatment zone is 5% or even 2% or less. Asdiscussed below, focal elevating elements can augment this advantageousfeature, even further lowering the ratio of the vessel contact area tototal treatment zone by providing separation between the vessel wall andat least a portion the circumferential members 12.

In certain methods, a vessel can be treated by implanting a plurality ofstructures, e.g., plaque tack 10′. The structures have a total contactarea with the vessel wall. The total contact area may be the sum of thevessel contact area of the individual structures. In the method, a totaltreatment zone area can be defined as the surface area between theproximal end of the most proximal structure and the distal end of thedistal most structure. In one method, the total contact area is no morethan about 55% of the total treatment zone area. More typically, thetotal contact area is between about 10% and about 30% of the totaltreatment zone area. In specific examples, the total contact area is nomore than 5-10% of the total treatment zone area.

The tack 10′ can also be understood to provide a relatively high openarea within its lateral edges compared to stents. Distinct fromtraditional stents, the track 10′ need not include sufficient metal toprovide a scaffolding function, to hold a vessel open. To accomplishmany of the contemplated treatments, the tack 10′ can be configured tolimit its contact to only a single point or a plurality of discretepoints, for example at one or more axial locations. The discrete pointscan be widely spaced apart, such as by being points on a circumferencethat are separated by spaces or, when applied, vascular tissue.

In some embodiments, the open area bounded by lateral edges of the tack10′ dominates the total footprint, as defined above. The open area ofthe tack 10′ can be defined as the sum of the areas of the cells 16 whenthe tack 10′ is in the fully expanded configuration, as defined above.The open area should be calculated at the outer circumference of thetack 10′, for example the area extending between the internal lateraledges of each of the struts. In this context, internal lateral edges arethose that form at least a part of the boundary of the cells 16. Invarious embodiments, the sum of the radially outwardly facing surface ofthe struts of the tack 10′ can be no more than about 25% of the openarea of the tack 10′. More typically, the sum of the radially outwardlyfacing surface of the struts of the tack 10′ is between about 10% toabout 20% of the open area of the tack 10′. In other examples, the sumof the radially outwardly facing surface of the struts of the tack 10′is less than about 2% of the open area of the tack 10′.

A single column design includes arrangements in a plurality of tackcells are oriented circumferentially about a central axis of the tack10′. Tack cells can come in many configurations, but generally includespaces enclosed by struts and are disposed in the wall surface of thetack. Open cell designs include arrangements in which at least some of aplurality of internally disposed struts of proximal and distalcircumferential members are not connected by bridges or axialconnectors. FIG. 5C shows that the inward apex 19 is unconnected to acorresponding inward apex on a mirror image ring 12. Thus, a portion ofthe cell 16 disposed above the inward apex 19 in FIG. 5C is open toanother portion of the cell 16 disposed below the inward apex 19. Opencell designs have increased flexibility and expandability compared toclosed cell designs, in which each internally disposed struts of aproximal circumferential member is connected to a correspondinginternally disposed struts of an adjacent circumferential member. Thecell 16 would be divided into two closed cells by connecting the inwardapex 19 to a corresponding inward apex on the mirror image ring 12. Asdiscussed above, closed cell plaque tacks can be suitable for certainindications and can include other features described herein. As shown,the single column open cell design extends along the midline C of thebridge (and also, in this embodiment, along the circumference of thetack 10′).

In one embodiment the cell 16 is identical to a plurality of additionalcells 16 that would be disposed circumferentially about the central axisof the tack 10′. The number of cells can vary depending on factors suchas the size of the vessel(s) for which the tack 10′ is configured, thepreferred arrangements of the rings 12, the number of bridges 14 to beprovided and other factors.

As discussed above, the tack 10′ can include proximal and distal rings12 connected by bridges 14. The proximal ring 12 can be disposed at aproximal end of the tack 10′. The distal ring can be disposed at adistal end of the tack 10′. In some embodiments, the distal ring is thedistal most aspect of the tack 10′ and the proximal circumferentialmember is the proximal most aspect of the tack 10′. The bridges 14 candivide an outer surface of the tack 10′ into cells 16 bounded by thebridges 14 and a portion of each of the proximal and distal rings 12. Inthe embodiment of FIGS. 5A-5C, the single column design is provided byproviding bridges at only one axial position and only a pair ofcircumferential members or rings 12. FIG. 5C includes the terms “distal”and “proximal” for reference purposes related to this and otherexamples, thus the ring 12 shown is the distal ring. In otherembodiments, the ring 12 shown can be the proximal ring.

As discussed above, the cells 16 can have one of many different shapesand configurations. FIG. 5B shows that, the cells 16 are aligned as arepeating pattern forming a single column open cell design along thecircumference of the tack 10′.

Conventional stent designs are generally relatively long (e.g., 4 cm andeven up to 20 cm when used in peripheral vasculature) from their distalto proximal ends. Where arranged with circumferentially disposed cells,conventional stents have a large number of columns of cells. Thesedesigns are burdened with repeating points of weakness and can generatestresses that become difficult to manage. As the device is put understress and strain, these conventional stents must find regions ofgreater pliability within the strut matrix. These strut regions absorbthe load throughout the system and under periods of repeated externalforces begin to fail, such as through metallurgical friction loading.

The single column configuration of the tack 10′ is not subject torepeated weak point loading due to movement of remote stent portionsbecause the tack does not have to be axially elongated to provideeffective tacking treatment. Other benefits that derive from theshortness include reduced friction at the interface with the cathetersheath during delivery and with the blood vessel wall. As discussedabove, the stress at the blood vessel wall interface is reduced due tothe lack of cell-to-cell dragging or pulling which in turn reduces thepotential that the tack will pull or drag adjacent cells increasingcellular inflammation or histological response along the lumen wall. Asingle column or other axial short configuration also reduces the stressalong each strut because the overall length of single column or otheraxial short structures or configurations are less affected by theanatomical motion (e.g., bending, twisting, and rotating). This results,at least in part, from the anatomy shifting around short structureswhile longer structures do not allow the anatomy to shift and thuslonger structures absorb more forces resulting from this anatomicalmotion.

Any motion between the surfaces of the tack and the blood vessel cancause rubbing and friction. If the motion is very small it can bedescribed as micro-rubbing, as discussed above. Even micro-rubbingproduces a negative effect on both the tack 10′ and the biological cellsof the blood vessel. For example, friction occurs when a portion of animplanted object moves while another portion is stationary or moving bya smaller amount. Differential amounts of moving over time weakens thematerial leading to fracture by processes such as work hardening. Thebiological cells become irritated by the friction and can respond byproducing an inflammation response Inflammation can drive a variety ofundesired histological responses including neointimal hyperplasia andrestenosis.

2. Controlled Angle of Struts

FIG. 5C shows that the tack 10′ has two circumferential members or rings12 which each have a plurality of internal angles, including α, and σ. Afirst angle α is defined at the first outward apex 24 between the struts26, 27 and a second angle σ is defined at the second outward apex 25between the struts 28, 29. In some embodiments, the first angle α can begreater than the second angle σ. For example, the first angle α can bebetween 43° and 53°, or between 45° and 51°. The second angle σ can bebetween 31° and 41°, or between 33° and 39°. In some embodiments, thefirst angle α can be about 48°, and the second angle σ can be about 36°.

In a preferred embodiment, the tack 10′ has an expanded outer diameterof 7.5 mm and the first angle α can be 47.65° and the second angle σ canbe 35.56°. In such an embodiment, the plaque tack 10′ can be formed froma tube stock with an initial outer diameter 4 mm. The tube stock can beexpanded to 7.5 mm and then heat treated in that shape. In someembodiments, the plaque tack 10′ can be made of a shape memory materialand the heat treatment step can be to engrain that particular shape intothe “memory” of the material. The plaque tack 10′ can then be crimped orcompressed and flash frozen in the compressed state to then be loadedonto a delivery device.

A beneficial feature of the tack 10′ is that the angle of the struts asthey meet at each apex can be controlled in at least one of an expandedand a contracted state. For example, the internal angles α, σ of theoutward apices 24, 25 can be controlled to be within ±5% of a selectednominal value. This control can be achieved for example, in the expandedstate during the heat treatment during the manufacture of the plaquetack 10′.

It has been found that control of the angles can beneficially offerrelief from imperfections in the manufacturing process. In some cases,the control of other dimensions can be relaxed if these angles aresufficiently well controlled. By controlling these angles, productionrun quality can be improved. Such control has been found to enablerepeatable, uniform, and balanced compressibility of the tack 10′ duringthe crimping cycle of manufacturing. These factors increase productionrun repeatability and offer ease of volume manufacturing which resultsin a reduction in overall cost of the part.

In addition, control of the apex angles allows the plaque tack 10′ tobetter distribute stresses along the circumferential members or rings12. The control of apex angles can be used to control or distributestresses within the ring 12, e.g., uniformly along the length of thestruts or non-uniformly to a region that can more robustly respond tostress loading. By distributing stress along the strut, the problematiclocalized stresses on the tack 10′, such as at vulnerable spots can beavoided during the expansion and crimping processes of manufacturing.

3. Inverse Tapering Struts

In some embodiments, such as that shown in FIGS. 5A-C, the width of oneor more of the struts 26, 27, 28, 29 of the tack 10′ can be different atdifferent locations, e.g., can vary along the struts. For example, thestruts can be tapered along their length. The taper can be the same ordifferent along each strut or along each type of strut. For example,each circumferential member or ring 12 can be made up of a pattern ofrepeating struts, with each type of strut having a particular taper.

FIG. 5C shows that the ring 12 has a first strut coupled with a bridge14 that is tapered such that a portion of the strut closer to themidline C (sometimes referred to herein as a medial portion or location)is narrower than a portion of the strut spaced farther away from themidline C (sometimes referred to herein as a lateral portion). A secondstrut is connected to the first strut at lateral ends of the first andsecond struts. The second strut can have the same or a different taper.For example, the second strut can also have a medial portion narrowerthan a lateral portion of the second strut. In addition, the secondstrut can be narrower overall than the first strut. A third strut can beconnected to the second strut at medial ends of the second and thirdstruts. The third strut can have a medial portion that is wider than alateral portion thereof. A fourth strut can be connected to the thirdstrut at lateral ends of the third and fourth struts. The fourth strutcan have a medial portion that is wider than a lateral portion thereof.The fourth strut can have the same or a different taper from the thirdstrut. For example, the fourth strut can wider overall than the thirdstrut.

FIG. 5C schematically illustrates the differences in the widths of thestruts in one embodiment. In some embodiments, the long struts 26 andthe long strut 27 have the same width at the same axial position and theshort struts 28 and the short strut 29 have the same width at the sameaxial position. The struts 26 and the strut 27 can have the same shape.The strut 28 and the strut 29 have the same shape in some embodiments.The shape of the struts 26, 27 can be different form the shape of thestruts 28, 29. In some embodiments, the long strut 26 and the long strut27 have different widths at the same axial position and the short strut28 and the short strut 29 also have different widths at the same axialposition.

In a preferred embodiment, the long struts 26, 27 are disposed at afirst circumferential location of the tack 10′ adjacent to one of themarkers 22. In particular, the strut 26 has a medial end connected to orforming a portion of one of the inward apices 18 and a lateral enddisposed away from the inward apex 18. The lateral end is coupled to thestrut 27 at or adjacent to the outward apex 24. The strut 26 has a widthW4 adjacent to the medial end and a width W2 adjacent to the lateralend. In this embodiment, the width of the strut 26 increases along thelength thereof from the width W4 to the width W2. The increase in widthalong the strut 26 preferably is continuous along this length.

Also, the sides of the struts 26 can be sloped relative to alongitudinal axis L_(A) of the strut 26. For example, a first side 48disposed between the longitudinal axis of the strut 26 and the strut 27can be disposed at an angle to (e.g., non-parallel to) the longitudinalaxis of the strut 26. In another embodiment, a second side 46 of thestrut 26 can be disposed at an angle to (e.g., non-parallel to) thelongitudinal axis of the strut 26. In one embodiment, both the first andsecond sides 46, 48 of the strut can be disposed at angles to thelongitudinal axis of the strut 26.

The strut 27 preferably also has different widths at different pointsalong its length. In particular, the strut 27 can be wider in agenerally lateral direction adjacent to the outward apex 24 than it isadjacent to the inward apex 19. As discussed above in connection withthe strut 26, the strut 27 can have side surfaces that are angledrelative to the longitudinal axis of the strut 27. The strut 27 can betapered between its ends, e.g., having a continuously decreasing widthalong its length from wider adjacent to the outward apex 24 to narroweradjacent to the inward apex 19.

The strut 28 extends from the strut 27 or inward apex 19. The strut 28can have a medial end that is wider than a lateral end of the strut 28and can have different widths at different points along its length. Theside surfaces can also be angled relative to the longitudinal axis ofthe strut 28.

Finally, a strut 29 can be connected to the strut 28 or outward apex 25at a lateral end of the strut 29. The strut 29 can have a medial endthat is wider than the lateral end thereof. The strut 29 can have ataper that is the same or different from the strut 28. For example, thestrut 29 can be wider overall than the third strut.

In one embodiment, the strut 26 can have a width W₂ of about 0.12 mm atthe lateral end near the outward apex 24 and a width W₄ of about 0.095mm at the medial end near the inward apex 18 and the strut 28 can have awidth W₆ of about 0.082 mm near the outward apex 25 and a width W₈ ofabout 0.092 mm near the inward apex 19. More generally, the change inthickness between W4/W2 expressed as a percentage can be between about70% and about 90% more typically between about 75% and about 85%, and incertain embodiments about 80%. The tapering can also be inverted, e.g.,with the struts tapered from the ends (e.g., lateral edges) toward themedial portion.

FIG. 5E illustrates another variation in which the width of one or moreof the struts of the tack can be different at different locations, e.g.,can vary along the struts. For example, a strut 28′ can be provided thatis similar to the strut 28 except that the strut 28′ is narrowest in amid-section N. The strut 28′ can have a lateral wide portion L adjacentto the outward apex 25 and a medial wide portion M adjacent to theinward apex 19. The width of the strut 28′ reduces along the lengththereof from the lateral wide portion L toward the medial portion M. Inone embodiment, the strut 28′ is continuously narrower along the lengthfrom the lateral end of the strut 28′ toward the midline of the strut.The strut 28′ can be narrowed such that the ratio of width at themidline to width at the lateral end of the strut 28′, expressed as apercentage, is between about 20% and about 85%. In some embodiments,this percentage is between about 35% and about 75%. The tapering can besuch that this percentage is between about 55% and about 70%. From themedial wide portion, the strut 28′ can be narrowed along the lengththereof. In one embodiment, the strut 28′ is continuously narrower alongthe length from the medial end of the strut 28′ toward the midline ofthe strut. The strut 28′ can be narrowed such that the ratio of width atthe midline to width at the medial end of the strut 28′, expressed as apercentage, is between about 20% and about 85%. In some embodiments,this percentage is between about 35% and about 75%. The tapering can besuch that this percentage is between about 55% and about 70%. Theembodiment of FIG. 5E provides a greater range for compression andexpansion in smaller diameter configurations. Smaller diameterconfigurations can be used in smaller body lumens, e.g., blood vessels.For example, a tack with this configuration can be formed out of 2.3 mmdiameter tubing, whereas the embodiments of FIG. 5C are optimally formedout of 4.5 mm diameter tubing. The configuration of FIG. 5E can be usedto make tacks that are suitable for a 4 French delivery device. Tacksconfigured as in FIG. 5E can have an unconstrained expanded size ofbetween about 4.5 mm and about 6.5 mm. In some embodiments, devicesincluding the configuration of FIG. 5E can have an unconstrainedexpanded size of between about 5 mm and about 6 mm, e.g., between about5.5 and about 6.0 mm. One embodiment expands to about 5.7 mm whenunconstrained.

A unique inverse taper or variation in width along the strut is achievedby inverting the orientation of the taper between the short struts 28,29 and the long struts 26, 27. The longer struts 26, 27 go from a narrowwidth near the inward apices 18, 19 to a broader width near the highoutward apex 24. Conversely, the shorter struts 28, 29 are the oppositewith a broader width near the inward apices 18, 19 to a narrower widthnear the low outward apex 25.

Through strategic selection of the width of the struts, as discussedabove, the plaque tack can distribute the stresses observed duringcompression and after deployment. This feature can also contribute tothe control of the stress by distributing the region of stress moreuniformly along the length of the strut. In some embodiments, it may bedesirable to distribute the stress non-uniformly to regions more able tohandle the stress.

4. Dual Amplitude Struts

As been discussed above, the ring 12 illustrated in FIGS. 5A-5C has anundulating sinusoidal pattern. The axial extent of the ring 12 can varyabout the circumference of the ring 12, for example providing aplurality of amplitudes as measured by the distance from an inward apexto an adjacent outward apex. The undulating pattern can have one or moreamplitudes, such as the dual amplitude configuration shown. In the dualamplitude configuration the plurality of struts 26, 27, 28, 29 extendbetween inward 18, 19 and outward apices 24, 25.

In some embodiments, the outward apices 24, 25 alternate between a highoutward apex 24 and a low outward apex 25. In this context “high”corresponds to a larger distance H1 as measured from a central zone ormidline C of the tack 10′ and “low” corresponds to a smaller distance H2as measured from the midline C (FIG. 5C).

The varying amplitude of the long and short sinusoidal struts describedabove can provide additional control of the plaque tack's functionality.In particular, it can enhance compression of the tack 10′ to provide agreater change in circumference from the fully expanded configuration toa compressed configuration when crimped during manufacturing. Greatercompressibility facilitates delivery in smaller vessels and a greaterrange of indication that can be treated because it enables a smallercrossing profile delivery system.

The height H₁, H₂ of the apices is measured from the center line C tothe top of the respective outward apices 24, 25. The dual amplitudesinusoidal patterned plaque tack 10′, such as that shown in FIGS. 5A-C,enables broad ranging conformable dimensions that can easily be scalableto different outer diameter designs. The open cell single column designallows broad range compression and expansion. This is partly due to thelength of strut available for effective expansion. The ease ofcompression is associated with the position of the apices disposed H₁and H₂ from the center of the tack, which permits these apices tocompress at a different locations instead of at the same laterallocation. If H₁ and H₂ of the apices are aligned (e.g., at the sameaxial location) they would press against each other during compressionlimiting the compression range.

The ranges of compression for the plaque tack 10′ have been measured to0.25 times nominal tube size in combination with ranges of expansion upto 2 times nominal tube size, although these are not the anticipatedlimits of the device. Combining these ranges the full range ofcompression has been measured at 0.125 times the heat treated outerdiameter. As discussed above in SECTION II.B.2, in some embodiments thenominal tube size is 4.5 mm and the tube is expanded to 7.5 mm in themanufacturing process. According to some embodiments, the distance fromthe midline C of the device to the apex of the longer struts H₁ isapprox. 3.0 mm, while the distance H₂ to the apex of the shorter strutsis approx. 2.6 mm. In some embodiments H₁ is about equal to H₂,alternatively, H₂ is about ½ or more, or about ¾ or more of H₁. In someembodiments, H₁ is between about 1.0 mm and 8.0 mm, or between about 2.0mm and 6.0 mm, or between about 2.0 mm and 4.0 mm.

In addition to the enhanced compressibility range, the energy stored inthe shorter amplitude struts offers additional control of the plaquetack 10′ during the release phase of delivery within the blood vessel.As the catheter sheath is retracted, the longer struts are uncoveredfirst followed by the shorter struts (FIG. 5C). This mismatch providesgreater retention forces to maintain the plaque tack 10′ in the deliverycatheter and thus provides greater control of the plaque tack duringdelivery.

FIG. 5F illustrates another embodiment of a plaque tack. In thisembodiment, the inward apex 19″ is positioned outward a distance H₃ fromthe inward apex 18. Thus, the struts 27″ and 28″ are similar to thestruts 27′, 28′ except that they are shorter as can be seen. Such aconfiguration offers additional benefits particularly in delivery.Though the plaque tack of 5F is illustrated with four different lengthstruts and outward apices 25, 24 that are spaced different lengths awayfrom the bridge members, it will be understood that the tack can also beconfigured in other ways. For example, the struts 28″ and 27″ can be thesame length with the outward apices 25, 24 also being the same distancefrom the bridge members while struts 26, 29 can be longer.

In some embodiments the length H₃ can be no more than about 5%, 7%, 10%,25%, 30%, 40%, 50%, or 75%, of the length of strut 26 or strut 29.

As has been mentioned, the plaque tack can be delivered in a highlycontrolled fashion. The different length struts and different positionsof the apexes can help facilitate a controlled release of the tack. Whenreleased from a delivery device, the different length struts expand atdifferent rates so that the energy stored in the struts is released instages and not all at once. Varying the width of each strut can alsohelp control the energy storage and release, as has been previouslydiscussed. Having an inward apex 19″ forward of the inward apex 18 adistance H₃ further helps to more evenly release the stored energy overtime. As has been mentioned, the distance H₃ can be a large distance ora relatively small distance compared to the length of the struts. Inaddition, once the inward apex 19″ has been released, a pad or foot 21is exposed (see FIGS. 5F and 5G). The foot 21 can be formed of theinward apex 19″ and the two struts 27″, 28″.

Once the struts from the first ring have been released from the deliverydevice, the foot 21 can reach a first expanded state. This can create aseries of feet 21 that extend annularly around the plaque tack. Theseseries of feet can help the plaque tack be delivered with high precisionbecause the feet can be in a position parallel to the wall of thevessel. The feet 21 can have a pre-full deployment diameter that is lessthan the full deployment diameter. After release of the rest of thetack, these feet can move into contact with the vessel wall in a quickfashion thereby minimizing movement of the plaque tack. Having feetparallel with the vessel wall can help reduce or prevent point pressureon the vessel wall when the tack is released. This may reduceinflammation or other undesired problems. This configuration can alsoreduce problems that are common in stents such as scrapping or draggingof the device along the vessel wall as the device is being released.This issue commonly occurs in stents because the device struts engagethe vessel wall at an angle as the stent is released.

In some embodiments, the feet 21 will be nearly fully expanded whilemuch of the rest of the plaque tack remains constrained within thedeployment catheter.

In still other embodiments, the feet can be released to a first expandedposition and then the feet can be moved to intermediate expandedpositions before the tack is released. For example, the length H₃ can bea relatively large distance so that the feet will be released beforemost of the length of the struts 26, 29 have been released. This type ofconfiguration may be used with fairly large vessels or spaces within anorgan.

The feet 21 can also help center the delivery device and/or preventrotation of the plaque tack. When a guidewire is used with the deliverydevice, the natural curves in the vessel may bias the guidewire andthereby the delivery device towards one side of the vessel. In anextreme example, the delivery device may be sitting on the vessel wall.Releasing the feet can force the tack and the delivery device away fromthe vessel wall. This is because as the feet are released to an expandedstate expansion of the device allows the feet to contact and push off ofthe vessel wall to begin to center the tack and delivery device. Even ifthe forces on the delivery device do not allow the delivery device to becentered by the feet, the feet can control the release and positioningof the tack so that the tack will be properly positioned and centered inthe vessel. Thus the feet can center and properly align the plaque tackwith the vessel wall independent of the delivery device orientation.

The feet will generally center the device for a short period of time,such as during one stage of delivery. This time period can be up to themidway point of delivery, such as until the bridge members are released.In addition, the feet generally center only a small portion of thedelivery device. For example, the feet can center about 3 to 5 mm of thedelivery device, about 3 to 5 mm on either side of the feet.

It will be understood that though the feet are shown with respect to atack, this concept can also be applied to other devices includingstents, vascular implants and still other types of implants.

The fact that the device can experience a large amount foreshortening ofthe axial length as it expands can also help to facilitate the correctplacement. For example, the plaque tack can foreshorten by at leastabout 15% in some implementations, at least about 20%, at least about40% or more, before the entire device has contacted the vessel wall andreached the deployed length. The deployed length of the plaque tack canbe less than two times the diameter of the vessel.

In some embodiments, the axial length of the tack after an unconstrainedexpansion is no more than about 95%, in some instances no more thanabout 90%, in some implementations is no more than about 85%, in someinstances no more than about 75%, in some instances no more than about60%, of the axial length of the tack when compressed within the deliverycatheter. For example a 5-6 mm tack can experience at least about 1 mmof foreshortening.

In some embodiments, the length of one or more of the struts can beincreased to increase the stability of the device. For example, strut26, and/or strut 29 can be lengthened compared to previous embodiments.The length of the strut may be between about 4 mm and 10 mm, or betweenabout 6 mm and 8 mm. In addition, the number of undulations and/orbridges can vary depending on the arterial size desired for the plaquetack. For example, a tack intended for deployment via a 3 French devicemay include three or four bridging members whereas a tack intended fordeployment via a 6 French device may include as many as 12 or morebridges. Thus, in some embodiments the plaque tack may have six cells.Other numbers of cells can also be used. FIGS. 5H through 5J showcertain examples of tacks where the undulations of the rings have beenmodified. In these embodiments, additional and/or larger feet arecreated by the modified undulations. In some embodiments, the additionaland/or larger feet can be expanded in steps so that a first set of feet21A can be released before a second set of feet 21B.

In this, as in many of the other plaque tacks disclosed herein includingthose shown in FIG. 5A through 5J, but not limited to these embodiments,the controlled expansion and delivery of the tack can be furtherfacilitated by the formation of a hinge 23 between the rings and thebridge 14 (see FIG. 5G). This hinge 23 is located effectively at thejuncture between the inward apex 18 where the ring connects to thebridge 14. This hinge 23 allows the individual rings to expand andcontract individually and separately from the bridges, the other ringand the device as a whole. As has been described, the hinge 23 combinedwith other features of the tack can allow the struts to expand atdifferent rates when the struts are of different lengths and can alsoallow the foot 21 to expand out separately from the rest of the tack. Inaddition, as will be described in more detail herein, the hinge alsocauses an expansion force on the bridge and therefore on the anchor 20,causing the anchor to secure to the sheath thereby securing the plaquetack within the delivery device during delivery, even as part of theplaque tack is being released. The inward apex 19″ can be positioned adistance H₃ from the inward apex 18 sufficient to allow the inward apex19″ to be released while the anchor digs into the sheath therebyretaining inward apex 18 closer to the sheath. This distance can be avery small or a large distance. In addition, in some embodiments, thedistance can be zero, or the inward apex 18 can be spaced farther outfrom the anchor 20 than the inward apex 19″. In a preferred embodiment,the inward apex 19″ is spaced outwardly from the inward apex 18 inrelation to the anchor 20, such as shown in FIG. 5F.

Another benefit of the bridge and strut configuration of the plaque tackis that one size plaque tack can be used in many different sizedvessels. The tack can be implanted to expand to one of an almostinfinite number of sizes between the compressed state and the fullyexpanded state. For example, in some embodiments, a 4 French plaque tackcan be used in an artery of between 1.5 to 4.5 mm, a 6 French device canbe used in an artery of between 3.5 and 6.5 mm, a 5 French device can beused in an artery of between 2.5 to 5.5 mm. In some embodiments, a 5French device can be used within an artery of between 2.5 to 6.5 mm. Itwill be understood that the length of the struts can be varied toincrease or decrease the range of vessel sizes into which a tack can bedeployed.

In some embodiments, the tack has a proximal foot 21, a distal foot 21and an intermediate section. The distal foot 21 is expandable to conformto the inside of a cylinder or to the vessel wall while the proximalfoot 21 remains within the deployment catheter or other delivery device.The distal foot 21 may be at least about 1 mm and in some embodiments atleast about 2 mm or at least about 3 mm but generally is no more thanabout 5 mm and typically is less than about 4 mm in axial length. Theproximal foot can be symmetrical with the distal foot, about the axialmidpoint of the tack. In some embodiments, the tack has a distal foot 21but no proximal foot.

Another benefit of the design of the plaque tack is seen when comparingits use in different sized vessels. As the size of the vessel decreasesthe ratio of the size of the tack verses the diameter of the vesselincreases, but the struts are also more aligned with the longitudinalaxis of the vessel. This helps to decrease the amount of tack or strutarea that is in contact with different cells of the blood vessel wall.This is because blood cells of many vessel walls are also longitudinallyaligned. Thus, as the vessel size decreases for a particular sized tack,the orientation of the struts will be more closely aligned with theorientation of the cells that make up to vessel wall. Thus, thisconfiguration helps to reduce the contact of the strut across separatecells thereby reducing friction, irritation and other inflammatorycellular responses. The orientation of the struts can be seen bycomparing the position of the struts in FIG. 7B with that of FIG. 7D.Though it should be understood that the plaque tack in the fullyexpanded state also greatly reduces the possibility of adverse cellularresponse as compared to other known devices as has been previouslyexplained.

5. Centrally Disposed Anchoring and Elevating Structure

FIGS. 5A-5C illustrate that the plaque tack 10′ can include centrallydisposed anchors 20. While the anchors 20 are primarily for securingloose plaque, as discussed above, their placement and configurationenhance the control of the deployment and the performance of the tack10′ once placed inside the blood vessel.

As discussed above, the plaque tack 10′ can be a self-expandingcircumferential structure and the anchors 20 can be disposed on an outerportion of the tack. The anchors 20 can be coupled with any portion ofthe tack 10′ but preferably are disposed adjacent to the midline C ofthe bridges 14 as discussed above. In one embodiment, the tack 10′includes two anchors disposed on either side of the midline C asillustrated in FIG. 5C. In another embodiment, a single anchor can beprovided on the midline C. In a further embodiment, at least threeanchors 20 can be provided, such as one on the midline and two on eitherside thereof as illustrated in FIG. 5C. The bridge 14 can have twoanchors on one side and one anchor on the other side connecting the twoother anchors, as shown in FIG. 5D. In FIG. 5D, an anchor 20′ is locatedat the center of the tack 10′ along its axial direction. This embodimentprovides at least one anchor 20′ that is located on both sides of themidline C. Also, the anchor 20′ can be located on an opposite side ofthe marker 22 from the anchors 20. As such, plaque can be anchored froma plurality of directions, e.g., a plurality of circumferentialdirections. In a further embodiment, the anchors 20 are not present anda single anchor 20′ located on the midline C is provided. The embodimentillustrated in FIGS. 5A-C could also be modified to include one or moreanchors on either side of the marker 22, where anchors are currentlyonly shown on one side.

In one aspect, the plaque interaction of the tack 10′ is primarilyprovided by the anchors 20 and to a lesser extent the bridges 14. Insome embodiments, the anchors can have a preferred penetration lengthinto the plaque of 0.01 mm to 5 mm. In certain variations, thepenetration length is within a range of about 0.03 mm to about 1 mm. Inother variations, the penetration length is within a range of about 0.05mm to about 0.5 mm. The bridges 14, which can be disposed at alternatinginward apices, as discussed above, can be configured to reside on atangential plane of a cylinder when the tack 10′ is fully expanded andnot being deformed by an outward structure. The tangent configurationcauses the anchors 20 to project outward toward from the cylindricalsurface of the tack 10′. In this outward projecting position, theanchors are adapted to engage plaque or other vascular deposits causingthe vessel to vary from its unobstructed fixed state, e.g. to beout-of-round.

The tangential projection of the anchors and bridges also advantageousenhances the control of the tack 10′ upon deployment. A technique fordeploying the tack 10′ involves positioning the tack in a hollowcatheter body. When positioned in the catheter body, the tack 10′ iscompressed to a compressed state. The rings 12 are highly conformal dueto their construction, discussed above. As a result, the rings fullyappose to the inner luminal surface of the hollow catheter body. Incontrast, the bridges 14 and anchors 20 are more rigid and therefore areless conformal and as a result bite into the inner luminal surface ofthe catheter body. This creates a retention force within the catheterand limits unintended movement of some or all of the tack 10′ toward acatheter deployment zone.

In some embodiments, the retention force of the barbs 20 is maintainedor increased after partial deployment of the tack 10′. In particular, aregion of relatively high flexibility can be provided at the junction ofthe bridges 14 and the rings 12. While high flexibility sections ofstents can be areas of concern, such is not the case in the plaque tack10′ for reasons discussed below. The flexible region can have anymaterial property or structure to enhance its flexibility at leastcompared to that of the bridges 14 such that upon movement of the ring12 on the leading edge of deployment, the tangential configuration andtendency of the anchors 20 to bite into the hollow elongate catheterbody is not diminished. Such is the case even though the leading edgering 12 may expand to at least one-half of its fully expanded size.

As shown, the bridge 14 is connected to each ring at the inward apex 18where at least a portion of the bridge 14 can be aligned, partially orsubstantially aligned with one of the struts that make up the ring 12 ashas been described. For example, as shown, the bridge 14 is aligned witha high amplitude sinusoidal section of the pattern. The region ofrelatively high flexibility can be disposed between the inward apex 18and the bridge 14.

In certain embodiments, expansion of the ring 12 may even cause theanchors 20 to rotate outward to increase the retention force in thecatheter body. For example, expansion of the strut 26 may cause aninward deflection of the inward apex 18. While ring 12 is expanding aslight rotation of anchors 20 may occur which may cause a torquedoutward deflection of the leading anchor and a corresponding torquedoutward deflection of the trailing anchor. With reference to FIG. 5C, ifthe depicted ring 12 is first expanded upon moving out of the hollowcatheter body, the anchor 20 to the right of the midline C may bedeflected inwardly toward the central axis of the catheter body but theanchor to the left 20 will be deflected outward to increase theretention force thereof. Thus, the plaque tack 10′ may be retained inthe catheter during such partial expansion. Due to this feature theplaque tack 10′ can be uniformly placed, as discussed further below inSection II.B.8.

The out-of-cylinder nature of the bridges 14 and anchors 20 also providebenefits to the deployed state. In particular, in some embodiments in anexpanded state, the plaque anchors 20 are disposed radially outwardly ofa cylindrical surface formed by the rings 12. The degree ofout-of-cylinder can depend on the application, but in general may besufficient to space at least a portion of the cylindrical surface fromthe inner walls of the vasculature when deployed. As such, the anchors20 or the anchors combined with the rings 12 can be configured as focalelevating elements, which are discussed below in SECTION III.

As the plaque tack 10′ expands within a blood vessel, the struts willengage the vessel wall and/or plaque. It is anticipated that in mostsituations, at least some of the struts will be deformed in response toirregularities of shape within the blood vessel. At the same time, thebridges 14 are less deformable and thus will resist such deformationretaining a circular configuration. The outward forces that are appliedby the strut members are transferred into those areas that are incontact with the blood vessel wall. In some cases, when the tack 10′conforms to an irregularly shaped blood vessel lumen, the rigid centralanchors become the region for blood vessel contact. The cumulativeoutward force of the struts in the rings 12 are applied through thebridges 14 to the anchors. Adjacent struts share their load with thecontact region pressing the blood vessel into an enlarged configuration,such as a conformed circle.

Such a configuration can provide benefits such as helping the plaquetack 10′ to remain in place after delivery and allowing the plaque tack10′ to respond dynamically to the movement and pulsing of the bloodvessel itself. In addition, this configuration can have the benefit ofreducing cellular response and device fracture by limiting strut fatigueand associated micro friction loading at the tack-blood vesselinterface.

In some embodiments, the bridge 14 can include one or more anchor. Insome embodiments, the bridge can be formed entirely of anchors.

In some embodiments, the plaque tack 10′ has a generally cylindricalshape. For example, the plaque tack 10′ may be cut from a metal tubesuch that the features of the plaque tack 10′ retain a generally curvedtop surface. Thus, in some embodiments, the bridge 14 and anchor(s) 20are also curved together with the rest of the top surface of the tack.Thus, the can anchors remain in-plane with the rest of the top surface,even as the device moves between expanded and compacted configurations.In such embodiments the anchor(s) can be forced out of plane when thetack expands into a non-round portion of a vessel, as is typical in adiseased artery or other blood vessel. Because of the flexibility of thetack, a certain portion of the tack may be forced into a non-roundconfiguration by a diseased portion of a vessel. As a result the anchoror anchors at that portion can project outward and engage the vesselwhile the other anchors may not extend outward or out of plane. As itwill generally be difficult to know where the diseased portion of thevessel will be located, in some embodiments, the bridge at every cellcan include at least one anchor at or near the centerline of the tack.Other configurations are also possible.

After deployment of the plaque tack 10′, the surgeon has the option ofplacing an angioplasty balloon at the site of the tack and inflating theballoon to press the anchor or anchors 20 into the plaque and/or wall ofthe blood vessel.

6. Flat Midline Markers

As discussed above, the plaque tack 10′ has one or more markers 22. Inone embodiment, a series of radiopaque markers 22 can be located on thetack 10′. In some embodiments, the radiopaque markers 22 are at themidline C of the device. The radiopaque markers 22 can be disposedbetween the two circumferentially oriented sinusoidal members or rings12.

In some embodiments, the radiopaque markers 22 (e.g., platinum ortantalum) can be disposed adjacent to the plaque anchors 20. Theradiopaque markers 22 can have one of many different shapes orconfigurations. In some embodiments, the radiopaque markers 22 have aplanar or flat structure. As shown in FIG. 5C, each marker 22 is coupledwith, such as by being press-fit or riveted into, a circular eyeletproducing a flat leveled surface with the eyelet. The markers 22 offerclear visibility of the tack 10′ in the catheter delivery system andprovide guidance to the clinician for accurate placement during theprocedure.

According to certain delivery methods, due to the co-placement of theanchors 20 and the markers 22 at the bridges 14 between the sinusoidalrings 12, the markers 22 can offer a visible clue to the clinician ofthe point when the release of the device will take place. For example,once the markers 22 meet a marker strip located at the tip of a deliverycatheter sheath the full device can be deployed.

Referring now to FIG. 5C1, a schematic representation of a tack 10′ isshown. As illustrated, the anchor 20 has an increased material thicknessverses the rest of the tack. This results in the anchor 20 also havingan increased radiopacity as compared to the rest of the tack,effectively converting the anchor into a marker.

7. Simultaneous Device Placement in the Vessel

The plaque tack 10′ can be configured for simultaneous placement withina blood vessel. Simultaneous placement of the plaque tack 10′ can bedefined as the entire plaque tack 10′ being released from the deliverycatheter prior to any of the distal apices of the plaque tack 10′contacting the blood vessel lumen where it is to be placed. This eventcan occur when the anchors 20 are completely uncovered by the cathetersheath allowing the entire plaque tack 10′ to expand against the lumenwall of blood vessel. The struts 26, 27, 28, 29 can be free floating,e.g., spaced from the vessel wall or applying negligible force to thewall, such that they do not contact the lumen wall prior to simultaneousplacement. For example, the anchors 20 may have the effect of spacing aportion or substantially all of the struts 26, 27, 28, 29 from thevessel wall. Other forms of focal elevating elements are discussed belowthat can be used to space the tack 10′ from the lumen wall.

Simultaneous placement offers the clinician the ability to controlplacement up until the markers 22 and/or anchors 20 are uncovered whichcan generate a full expansion event (struts adjacent to or contactingthe lumen wall). In some embodiments, the full expansion event does notoccur until the anchors 20 are uncovered due mainly to internal forcesof the tack 10′ urging the anchors 20 to engage the delivery sheathdescribed above.

Another benefit of simultaneous placement is the reduction of anyinadvertent dragging or pushing of struts against or along the lumensurface during the placement of the plaque tack 10′. Due to thecomplexity and variation of disease, location of placement, anddissections morphology, the ability of the outer surface of the plaquetack 10′ to contact the lumen wall all at the same time is dependant onthe deployment circumstances. However, the ability of the plaque tack10′ to contact the lumen wall completely upon release from the cathetersheath within fractions of a second has been observed.

8. Low Slope Force Curve

Another unique aspect of the plaque tack 10′ is that it can beconfigured with a force curve with an extended area having a low slope.A force curve, such as those illustrated in FIG. 6A, shows the amount ofexpansive force exerted by or on a self expanding plaque tack 10′ orstent when moving between a compressed state and an expanded state. Theexpansion force of a device can be a factor in choosing the correctdevice to be placed in a particular blood vessel.

Still referring to FIG. 6A, the force curves of a SMART stent (i.e., aS.M.A.R.T.® Control transhepatic biliary stent by Cordis Corporation),and two different sized plaque tacks, including a plaque tack having thewall pattern illustrated in FIG. 5A. The chart shows the radial force inNewtons (N) on the y-axis and the outer diameter of the device inmillimeters (mm) on the x-axis. As the device is expanded or moved fromthe compressed state to the expanded state, the outer diameterincreases. Because the devices are self expanding, they have a setamount of stored potential energy. When released, the potential energyis converted into kinetic energy as the internal forces try to restorethe device to its expanded shape. The kinetic energy can then have animpact on the blood vessel when the device is implanted. Also, if theplaque tack 10′ is not fully expanded a generally constant force will beapplied to the vessel wall that corresponds to the remaining potentialenergy stored in the tack 10′.

FIG. 6A shows a first line A1 showing the compression of a 4 Frenchplaque tack 10′ from approximately 5.5 mm to approximately 1.5 mm ofcompressed diameter. After a gradual slope region between about 5.5 mmand about 4.5 mm, the slope of the force for each incremental reductionin diameter is greatly reduced, providing a narrow band of forcerequired to fully compress the tack 10′ from about 5 mm to about 1.5 mm.This portion of the force curve is very flat, meaning that the appliedcompression force does not greatly increase as the tack 10′ approachesits fully compressed state. The force curve of the plaque tacks 10′ uponexpansion is illustrated by a second line B1 extending from 1.5 mm ofcompressed diameter to about 5.5 mm of expanded diameter. This portionof the curve can be thought of as the working portion, in which theforce on the Y-axis is the force that the plaque tack 10′ would apply toa vessel wall upon expansion. For example, if the plaque tack 10′ weredeployed in a vessel lumen having a bore of about 4.0 mm, the outwardforce of the tack 10′ on the wall would be around 1.0 Newton (N).

A 6 French plaque tack is also shown as indicated by lines A2 and B2.The 6 French tack is shown being compressed from a diameter ofapproximately 7.5 mm to approximately 3.0 mm. The 6 French tack exhibitsa force curve very similar to the 4 French device, shifted slightly toreflect the difference in diameters. Here the force to compress thedevice (line A2) is shown having a gradual slope region between about7.5 mm and 6.0 mm and then it is very flat between about 6.0 mm and 3.0mm. Upon expansion as shown by line B2, the 6 French tack also exhibitsa low outward radial force. The force curve of the 6 French plaque tackupon expansion is illustrated between a diameter of about 2.0 mm toabout 7.5 mm. As can be seen, if the 6 French plaque tack were deployedin a vessel lumen having a bore of about 5.0 mm, the outward force ofthe tack on the wall would be less than 1.0 Newton (N).

FIG. 6A also shows the crimp performance of a SMART stent in a similartest at lines A3 and B3. As discussed above in connection with otherprior art stents, the SMART stent is a longer structure than the plaquetack 10′. In particular, the S.M.A.R.T.® stent tested was 40 mm longwith a 8 mm unconstrained outer diameter, whereas the 6 French tack thatwas tested was 6 mm long with a 7.5 mm unconstrained outer diameter.However, it is believed that the comparison between the plaque tacks andthe SMART stent illustrates a difference that would still manifest witha comparable length version of the SMART stent. As shown on the graph,the line B3 shows a much higher force required to compress the SMARTstent in the range from just over 8 mm to about 6.5 mm. At about 6.5 mm,the slope of the compressive or crimp force decreases and then increasesat a much slower rate. The outward force at the fully crimped state ismuch higher than that measured in the plaque tacks. Line B3 illustratesthe working zone of the SMART stent that was tested. Line B3 shows theoutward force over the range of expansion from about 2 mm to about 6 mm.As can be seen, the slope of line B3 is much greater at all points alongits range between 2 mm and 6 mm than that measured in the plaque tacks.The practical effect of this higher slope is that the SMART stent ismuch more sensitive to changes in the bore size of the vessel into whichthe expanded device is deployed.

As can be seen in FIG. 6A, in some embodiments of plaque tack, a lowslope of the force curve can be essentially flat over about a 3 mm ormore outer diameter expansion range. In other embodiments, a low slopeof the force curve can be over a 2.5 mm outer diameter expansion rangewith a change in force of change less than 1 N. Factors in the abilityof the tack to have a broad range where the radial forces change lessthan 1 N include the midline anchors, dual amplitude struts, and thevarying strut thicknesses, discussed above.

The tack is radially self expandable through a range of at least about 2mm, generally at least about 3 mm and typically through a range of atleast about 4 mm or 5 mm, while exhibiting a radial expansion force ofno more than about 5 N at any point throughout the range. In someembodiments, the maximum radial expansion force throughout the expansionrange is no more than about 4 N and preferably is no more than about 3N. In one embodiment, the tack is expandable over a range of at leastabout 3 mm (e.g., from about 3 mm to at least about 6 mm) and the radialexpansion force is less than about 3 throughout that range. Generallythe change in expansion force will be no more than about 3 N andpreferably no more than about 2 N throughout the expansion range. In oneembodiment, the expansion force drops from no more than about 2 N at 3mm diameter to no more than about 1 N at 6 mm diameter. Typically thedifference between the radial force of compression and the radialexpansion force at any given diameter throughout the expansion range isno more than about 4 N, generally no more than about 3 N, preferably nomore than about 2 N and in one embodiment is no more than about 1 N. Inone implementation, the tack is expandable throughout a range whichincludes 3 mm through about 6.5 mm and the difference between thecompression force and expansion force at each point along thecompression/expansion range differs by no more than about 2 N andpreferably by no more than about 1 N.

In general, the outward force of the plaque tack 10′ is preferred to beas low as possible, while providing sufficient force to hold the plaqueagainst the lumen wall through a wide range of luminal diameters. Whenforce is elevated, e.g., by two to three times the sufficient holdingforce, adverse side effects can occur. These can include irritating thecells of the vessel wall that are in contact with the device, which canlead to re-stenosis. Although a very low force device is preferred forthe typical treatment, higher force devices may be useful where looseplaque is found at calcified lesions.

One advantage to having a slow change in force as the device isexpanding is the ability to predict the energy that the blood vesselexperiences independent of the lumen diameter. Another value would bethe reduction of necessary inventory for hospitals. For instance, it hasbeen found that two part sizes of the tack 10′ shown in FIGS. 5A-C canbe used for plaque tacking treatments in blood vessels locatedthroughout the leg, from hip to ankle. This is believed to be due ingreat part to the tack 10′ having a slope of less than −0.3 N/mm.

C. Plaque Tack Design Parameters

One purpose of the plaque tack described herein, as distinct fromtraditional stenting, is to reduce the amount of implanted foreignmaterial to a minimum while still performing focal treatment of theblood vessel condition so as to cause a minimum of blood vessel wallreaction and adverse post-treatment restenosis. The plaque tack isdesigned to have substantially less metal coverage and/or contact withthe blood vessel surface, thereby inciting less acute and chronicinflammation (See FIG. 6B). Reduced contact area of implanted materialagainst the blood vessel wall is correlated with a lower incidence ofintimal hyperplasia and better long-term patency. Substantially reducedlength along the axial distance of the blood vessel permits a moretargeted treatment, correlates with less foreign body coverage of theblood vessel surface, avoids covering portions of the surface that arenot in need of coverage, and correlates with both early and lateimproved patency of blood vessel reconstructions.

The plaque tack can be deployed only where needed to tack down plaquethat has been disrupted by balloon angioplasty or other mechanisms.Rather than cover an entire area of treatment, the plaque tack can beplaced locally and selectively, for example, not extending into normalor less diseased artery segments (See FIG. 6B). This permits the bloodvessel to retain its natural flexibility because there is minimal to noscaffolding when a small profile tack is used locally or even whenmultiple tacks are spaced apart over the area of treatment. Stillfurther reduction in the pressure profile can be achieved by using“points-of-contact” to achieve higher pressure at focal points andlifting the neighboring strut section away from the blood vessel wall toreduce the overall load of the outward pressure elsewhere on the tackstrut structure.

One parameter for design of a plaque tack is having a tack axial lengthto expanded diameter (L/D) ratio of no more than about 2.0, often nomore than about 1.5 and in some implementations no more than about 1. Inone embodiment, the tack has about an L/D ratio of 0.8. That is, thelength of the tack along the axis of the blood vessel is about equal toor less than the expanded diameter of the tack. The preferred plaquetack is thus shaped like an annular ring or band, whereas the typicalstent is shaped like an elongated tube. The small-profile tack can thusbe used locally for targeted treatment of disrupted regions of the bloodvessel surface with a minimum of foreign material coverage or contact.Tests show that a plaque tack with an axial length/diameter ratio ≤1causes almost no biological reaction or subsequent blood vesselnarrowing in comparison to a traditional stent where the axial length isgreater than the diameter, and usually much greater. Tests indicate thatdevice L/D≤1 results in a reduction in scaffolding much less than thatof the typical stent and causes less arterial wall reaction. Forapplication at sites of small dissection after balloon angioplasty, aplaque tack of minimal footprint may be used such as a single, thinring-type tack with an L/D ratio in the range of 1/10 to 1/100.

Studies on stenting have shown that the axial length of a stent iscorrelated with a tendency for occlusion in multiple vascularterritories. The more stent axial length that has been placed, thehigher likelihood that the reconstruction will fail. The axial length ofa stent is also directly linked to the frequency and tendency of thestent to break when placed in the superficial femoral artery. Themedical literature indicates that the superficial femoral arteryperforms like a rubber band, and it is likely that changes to thenatural elongation and contraction of the superficial femoral arteryplay a significant role in the failure mode of superficial femoralartery stents. In contrast, the small-profile plaque tack can beimplanted only in local areas requiring their use, thereby enabling theblood vessel to retain its natural flexibility to move and bend evenafter the surface has undergone tacking. Multiple tacks may be implantedseparated by regions free of metallic support, thereby leaving theartery free to bend more naturally.

Outward radial pressure exerted on the blood vessel wall can also besubstantially reduced by the small-profile tack design, even whenmultiple tacks are used in a spaced-apart configuration. To minimizethis outward force while still providing the required retention ofdissections against the arterial wall, a series of anchor barbs or focalelevating elements can be utilized. The presence of these featuresapplying focal pressure to the wall of the artery allows the rest of thetack to apply minimum outward force to the artery wall. The points whichapply the pressure can be very focal, and this is where the most forceis applied. The focal nature of the application of the pressure exertedby the tack also minimizes the structural effects of the device.Uniformly distributed anchors or focal elevating elements can provide adistribution of radial energy maximizing the tendency to form a circularlumen.

Another important parameter for design of a plaque tack is the ratio ofVessel Coverage Area (C) to Total Vessel Surface area (TVS). In onedefinition, the value C is the length of the prosthesis (e.g., stent ortack) times the average circumference of the vessel in which it isplaced and the value TVS can be the length of the lesion or arearequiring treatment times the same nominal circumference. This can alsobe simplified to a ratio of total length of the prosthesis when expandedto the nominal circumference divided by the length of the lesion in thevessel. These concepts can be applied to one tack device or when severalspaced-apart tack devices are placed across the length of a blood vesseltreatment area. Where multiple stents or tacks are used, a simplifiedratio could be total non-overlapping length divided by lesion length orcould be the sum of the length of the prostheses divided by the sum ofthe length(s) of the lesion(s). For a plaque tack, the C/TVS ratio is inthe range of about 60% or less, whereas for a stent it can be 100% ormore (if applied to overlap the treatment site).

For a focal lesion, the conventional treated vessel length is X+10 mm to20 mm where X is the length of the lesion and the added length isadjoining on normal or less diseased artery proximal or distal to thelesion. In traditional stenting the entire treated vessel length wouldbe covered with a stent. For example, in the case of a 2 cm lesion, thetreated vessel length would be 3 to 4 cm (usually a single stent of thislength would be selected), so that C/TVS is 150%-200%. In contrast, withtack placement about ½ of X would be covered, and none of the adjoiningnormal or less diseased artery would be treated. For example, in a 2 cmlesion, approximately 1 cm would be covered, so that the C/TVS ratio isabout 60% or less. An advantageous aspect of this innovative approach isplacement of bands only in regions of dissections requiring vasculartacking.

As described previously, in some embodiments, a tack device 10′ isformed with rings or mesh bands 12 connected by longitudinal bridgemembers 14 (FIG. 5A). In the figure, the tack 10′ is shown compressedfor delivery in a blood vessel. When expanded, the diameter of the tackdevice can be about equal to the axial length of the tack device.

FIG. 6B illustrates the use of multiple tack devices which are spacedapart over a length of blood vessel at a treatment site as compared to atypical stent. Preferably, the spacing between tack devices is at leastthe axial length of the tack device. Note that the spacing betweenadjacent tack devices leaves untreated vessel area. A typical stent isshown in the upper part of the figure compared to the use of 6spaced-apart tack devices at the bottom part of the figure. In thisnon-limiting example, the overall length of treatment area is 6.6 cm(the same length of the stent) while each band is shown as 6 mm longseparated by 6 mm spaces. Therefore, the Vessel Coverage Area for thestent is the same as Total Vessel Surface area (=6.6 cm×0.6π, or 12.44cm²) which gives a C/TVS ratio of 100%. For the series of spaced-aparttack devices, C is equal to 6×0.6 cm×0.6π, or 6.78 cm², while TVS is12.44 cm², therefore the C/TVS ratio is equal to 54.5%.

When two or more stents need to be employed over an extended length oftreatment site, it has been a conventional practice to overlap adjoiningstents to prevent kinking between stents. Due to the increased metallattice, the region of overlap becomes highly rigid and noncompliant.This noncompliant doubly rigid region further limits the naturalarterial flexibility and increases the tendency for restenosis. Stentfractures occur more frequently in the superficial femoral artery wherethis bending has a high frequency and are common when multiple stentsare deployed and overlap. Stent fractures are associated with a higherrisk of in-stent restenosis and re-occlusion. In contrast, the plaquetacks are designed to be applied in local areas and not to beoverlapped. Optimal spacing is a minimum of 1 tack axial length apartfor tacks. This permits the artery to maintain its flexibility, and onlya half or less of the treated length of the artery will be covered withmetal. It should be noted that in the case where restenosis occurs aftertack placement the overlapping of the entire treated length with a stentstill allows the stent to retain its patency. This is due to therepeated pattern of regions where no tacks are placed offering regionsof relief and the artery to flex.

The literature in the industry has noted that important factors in stentdesign may be the ratio of Relative Metal Surface Area (RMS) and thenumber of longitudinal segments in the device structure, for example, aspresented by Mosseri M, Rozenman Y, Mereuta A, Hasin Y, Gotsman M., “NewIndicator for Stent Covering Area”, in Catheterization andCardiovascular Diagnosis, 1998, v. 445, pp. 188-192. More particularly,for a given metal surface area, a higher number of longitudinal segments(each of which is thinner) can reduce the size of the gap betweenadjacent segments, reducing the tendency for prolapse. As adapted fromthe RMS measure, an equation for Effective Metallic Interface (EMI) maybe used to compare the embodiment of the tack device with longitudinalbridging members to a typical stent, as follows:

${E\; M\; I} = \frac{\left( {1 + n^{2}} \right)C}{\sum\limits_{s = 1}^{x}({lw})_{S}}$

Where x is the number of sections of metal, l is an individual metalsection length, w is an individual metal section width, C is the vesselcoverage area underneath the device (lumen surface), and n is the numberof bridge members longitudinally connected between circumferentiallyoriented segments. The summation found in the denominator can beinterpreted as the total metal surface area. The embodiment of the tackdevice with longitudinal bridging members has an EMI≤10, whereas the EMIof a typical stent would be several times greater. This low EMI is dueto the nature of the tack design having a small foot-print and minimallongitudinal bridges while a stent typically has a large foot-print andwould be a multiple several times that.

To further reduce the EMI through the inclusion of lift-off-bumpfeatures (such as anchors, barbs, or focal elevating elements), animproved EMI_(F) can be obtained for the Tack Effective Metal Interfaceas provided with floating elements (see FIG. 9). EMI_(F) can be definedas:

${E\; M\; I_{F}} = \frac{C\left( {1 + \left( {n - n_{F}} \right)^{2}} \right)}{\sum\limits_{s = 1}^{x}\left( {{lw} - {l_{F}w_{F}}} \right)_{S}}$

Where all variables are the same as those in the EMI equation with theaddition of I_(F) is an individual metal section length that is not incontact with the artery (floating off the artery), and w_(F) is thewidth of the same section. If no floating sections exist then n_(F)=0and l_(F)w_(F)=0 and therefore EMI_(F)=EMI.

The inclusion of metal sections that are floating (floating lengthl_(F), floating width W_(F), and number of floating bridges n_(F),)reduces the EMI further which is captured mathematically as a summationwith negative variables in the EMI_(F) equation.

The presence on the plaque tack of lift-off-bump features (such asanchors, barbs, or focal elevating elements) minimizes the pressure ofthe overall structure upon the blood vessel wall by transferringregional outward forces to focal pressure points, thereby applying ahigher pressure at the focal points. The presence of the lift-off-bumpfeatures applying focal pressure to the artery wall allows the rest ofthe tack to apply minimum outward force to the artery wall. Wherever thelift-off-bump features are placed, the outward radial energy ismaximized at that region, producing a slight outward bowing of thearterial wall. The outward bowing can be used for arterial shaping ormolding, for example, 5 or more uniformly distributed focal points canbe used to form a circular lumen. Circular lumens offer additionalbenefit from the standpoint of the vessel wall interaction, independentof the vascular injury.

In any of the embodiments herein described, the plaque tack device maybe made from Nitinol, silicon composite (with or without an inertcoating), polyglycolic acid, or some other superelastic material, aswell as stainless steel, tantalum, a cobalt chromium alloy,bioabsorbable or bioresorbable materials (includingbioabsorbable/bioresorbable metals) or a polymer. The strip of materialcan be created from ribbon, round or rectangular wire or a sheet ofmaterial processed through photolithographic processing, laser or watercutting, chemical etching or mechanical removal of the final shape, orthe use of bottom up fabrication, for instance chemical vapor depositionprocesses, or the use of injection modeling, hot embossing, or the useof electro or electroless-plating. It may be fabricated from metal,plastic, ceramic, or composite material.

The plaque tack device is designed to be inherently self-aligning, i.e.,its mechanical installation can accommodate small misalignments. Byreducing stress in the strut members while gripping the arterial wall inthe center of the design, the tack self aligns with the arteriallongitudinal axis. Design features that offer stress relief and provideuniform distribution of the unfolding struts include narrow spacing ofthe anchors, non-uniformly thick struts, and anchors heads that areangled to reduce device from springing forward during delivery. Asdiscussed above, circumferentially oriented anchors located at eachbridge member offer gripping force with the catheter tip and embeddingfeatures when lying on the artery wall. These design features serve tofacilitate placing the tacks in specific locations within diseased bloodvessels.

III. Improvement of Focal Elevating Elements

FIGS. 7A-D show a plaque tack 10″ that is similar to that of FIGS. 5A-Cexcept as discussed below. In particular, the plaque tack 10″ includes afeature that reduces the amount or character of interactions between theplaque tack 10″ and the vasculature by elevating a portion of the plaquetack 10″ off of the vessel wall when deployed.

In particular, the high outward apex 24′ formed by the struts 26 and 27is bent or turned upwards, or radially outwards, to form a focalelevating element (FEE) 32. FIG. 8 shows a schematic view of the FEE 32.In this embodiment, the high outward apex 24′ is bent to form an anglewith the struts 26 and 27. In this way the FEE 32 can help minimize theamount of the tack 10″ that is in contact with the plaque and/or vesselwall while also localizing the forces at few points to more securelyplace the plaque tack 10″. These as well as additional benefits will bedescribed in more detail below.

A plaque tack devices may be provided with focal elevating elements onthe annular periphery of the device. The focal elevating elements aredistinguished from the anchors and barbs generally having greater plaqueor arterial wall penetration to anchor or stabilize the tack in theblood vessel.

The focal elevating elements may or may not penetrate but still offerregional strut elevation and are preferably placed at apices of strutsor periodically along (e.g., perpendicular to) strut lengths. For bothanchors and focal elevating elements the size of the interface betweenthe tack and the arterial wall is preferably equal to or shorter thanthe strut width in at least one direction. The focal elevating elementscan be similar to anchors but either do not penetrate or penetrate thetissue only slightly, thereby minimizing the amount of material surfacearea in contact with the plaque, and offer a set of relief sections forthe outward pressure of the tack device adjacent to the focal elevatingelements, thereby minimizing the friction generated at the blood vesselwall.

The focal elevating elements can be formed and configured on the annularperiphery of the tack device in a similar manner as described for theprevious tack device embodiments and can include the raised contactsections in addition to anchors or sharp points. The contact sectionscan provide improved tacking characteristics in that they increase thecontact forces at the contact sections by compressing the plaque at thecontact regions and decrease the outward force at the sectionsneighboring the focal elevating element. This offers regional pressurerelief in some sections and increase contact pressure at the bumps orsharp points collectively offering a reduction in trauma and cellularresponse of the blood vessel wall.

Because the tack device is held in place by its own pressure exerted onthe blood vessel surface, it is susceptible to friction, includingslight movement between the device and the vessel surface. Every timethe organ moves (e.g., the leg during ambulation), the artery moves. Itcan be inferred that when the artery moves the working device sittingwithin the artery also moves but not necessarily every point of contactmoves in synch with each other. Whenever there is even a small mismatchin movement between the artery and the device the artery and device rubagainst each other promoting cellular reaction and device failure. Ithas been deduced from experimental that this rubbing may irritate theendothelium causing an inflammatory response. In some embodiments,strategically placed focal elevating elements (FEEs) are implemented toreduce the overall regional friction load (thought to be a source ofinflammation, cellular proliferation, and the healing response thatleads to restenosis) of the area being held open.

As an example, a blood vessel such as the popliteal that is cyclicallyshortened and elongated is believed to have a cellular or tissuestructures that elongate and compress in a direction parallel to theaxis of the vessel. The natural behavior of this cellular or tissuestructure involves a significant amount of local movement along thisaxial direction. If an implant to be placed in such a vessel is designedto contact the vessel wall in a direction transverse to this axialdirection, the natural behavior of these tissues or cells will begreatly disrupted. For example, the tissue will be constrained and thenatural movement will be greatly reduced. Also, rubbing can occur alongthe edges of the transversely contacting structure, resulting infriction and/or abrasion of the tissue and corresponding inflammation.FEEs, in contrast, reduce the disruption of the natural behavior of thetissue or cells. If incorporated into a tack device or other prosthesis,FEEs can focus the contact at zones that are spaced apart along adirection transverse to the predominant direction of motion (e.g., theaxial direction in the case of the popliteal or similar vessel). Betweenthese zones of focused contact corresponding to the FEEs, theinteraction of the compressing and elongating tissue or cells with thestructure of the implant is greatly reduced. In this in-between zone,the motion between the compressing and elongating tissue or cells canapproach that of the tissue or cells before the implantation of theprosthesis. Raised sections produced by the FEEs limit the histologicalresponse of the tissue and also the fatigue of the device by limitingthe contact between the device and the tissue.

Independent of the overall amount of contact and number of FEEs, thetack devices smooth the lumen wall, and allow more natural vesselmovement. Where FEEs offer the greatest value is in there ability toreduce the amount of interaction between tissue or cells that move,elongate or compress, which can produce rubbing or friction to suchtissue or cells. It is this highly localized movement or“micro-movement” that increases the cellular response of the bloodvessel surface to the foreign device.

The focal elevating elements are designed to reduce effective metalinterface (EMI) by minimizing the overall material contact with theblood vessel surface. The focal elevating element (FEE) is preferablyconfigured as a narrow, lifted feature with enough height to liftadjacent strut sections of the tack device off from contact with thearterial wall in order to reduce the surface area of foreign material incontact with the arterial wall. Reducing the contact burden is ofparticular value when the strut members are connecting circumferentialrings or circumferentially oriented strut bands. Strut sections orientedagainst the natural grain of the cellular orientation that are incontact with the blood vessel walls can produce microfriction when theymove or rub against the blood vessel walls. By reducing the foreignmaterial contact area against the blood vessel wall, the tendency forproduction of microfriction contact is reduced.

Referring to FIG. 9, a schematic diagram illustrates some of the designassumptions for the use of focal elevating elements on a plaque tackdevice. In the figure, h refers to the height of the focal elevatingelement that is extended out of the blood vessel (note: the penetrationdepth of the focal elevating element that is anchored into the artery orplaque body is not included in this calculation), w refers to the widthof the focal elevating element (at its base), and l_(F) refers to theadjacent strut surface lifted off the arterial wall (mathematicallysimplified as a straight line). The struts adjacent to the focalelevating element may be fabricated with shape memory materials ordesigned as a compression wave providing compensation for lumen diametervariations. The strut forces adjacent to the focal elevating elementsproduce an outward bowing of the struts produced by the forces of thestruts wanting to expand until they are in contact with the blood vesselwall. l_(A) refers to the length of arterial wall that is kept out ofcontact with any adjacent strut structure by the focal elevatingelement.

One or more of the features labeled in FIG. 9 can be varied to provideadvantageous FEE performance. For example, h can vary depending on thesize of the delivery catheter for instance a 4Fr provides an h of up to150 um. In certain embodiments, a tack with FEEs configured for deliveryin a 4Fr catheter can have h of about 100 um or less. An exampleembodiment that can be deployed with a 4Fr delivery system has one moreFEEs with h of about 75 um. Larger tacks with FEEs, e.g., configured fordelivery in a 6Fr catheter can have an h of up to about 300 um and insome cases 225 um or less. An example embodiment that can be deployedwith a 6Fr delivery system has one more FEEs with h of about 200 um.Still larger tacks with FEEs, e.g., configured for delivery via an 8Frcatheter, could have an h of up to 950 um while in certain embodimentsFEEs of up to 500 um could be provided. An example embodiment that canbe deployed with an 8 Fr delivery system has one more FEEs with h ofabout 400 um.

Any of the foregoing dimensions of h may be combined with a variety ofdimensions of W of the FEE. The W dimension would typically be the widthof the strut but could be as little of 50% the strut width and may bebetween about 50% and about 100% the width of the struts at the locationof the FEE. I_(f) and I_(a) are a function of W, the radial force of thesystem, the topography of the lumen, and the delivery device, e.g.,varied if a balloon is used to press the device into the artery. If wejust look at W (non elastic system) then I_(a) may be about equal to thelength of the strut. As outward force (both from the elastic nature ofthe metal and the balloon assist) increases then I_(a) can be reduced,approaching 0. However, in various embodiments, I_(a) is at least about20 um.

The focal elevating elements may be formed as cylindrical, rectangular,linear, spherical, conical, tear dropped, pyramidal, or inclinedelements on the annular periphery of the tack device. They can be formedby bending or stamping a section of the tack structure, by an additiveprocess (such as by welding or annealing on a peripheral surface), by asubtractive process (such as by grinding or etching away surroundingmaterial so that the bump element is higher than the surroundingsurface), or by modifying small sections of the peripheral surface to behigher than the surrounding surface before or after sheet or tubecutting. For example, one method of modification of small sections of amesh tack structure is by knotting, twisting, bending or weaving smallsections of the wire mesh to produce raised elements from the meshsurface which are the interface with the artery wall of the tackdevices.

Properly oriented and symmetrically positioned focal elevating elementscan provide foci for expansion force. As the device exerts outwardforces and the artery exerts inward forces, the focal elevating elementscan be positioned at strategically located positions reducing theoutward pressure of strut sections neighboring the focal elevatingelements.

Both anchors and focal elevating elements can offer strategic advantagesthat include: the reduction in pressure burden across the tack struts byreducing the contact area and translating the outward forces to theanchors and focal elevating elements, minimizing surface contact whichoffers a reduction in the tendency of frictional loading driven by micromovement between the arterial wall and the tack strut, and thestabilization of anchoring the tack where the anchor or focal elevatingelement penetrates the vessel wall a fraction of the features height.

Because the tack device is held in place by its own outward forcepressure exerted on the plaque and blood vessel surface, it may besusceptible to friction, i.e., slight movement between the device andthe vessel surface. FIG. 10 illustrates the forces at play between thetack's focal elevating elements and the arterial wall. F_(T) is thecircumferential force exerted by the tack device against the arterialwalls force, F_(A). F_(FEE) is an additive circumferential force at thefocal elevating element generated by the design and material choice andF_(F) is the frictional force of the artery generated when the arterychanges its orientation or shape due to body forces. Every time a bodyparty moves, the blood vessels move slightly as well. The focalelevating elements can be strategically positioned to reduce localfriction loading which may cause inflammation, cellular proliferation,or bodily response that leads to restenosis.

The number and locations of focal elevating elements can affect theoverall Relative Metal Surface Area (RMS) which was explainedpreviously. The focal elevating elements may be positioned along thelengths of the tack device surfaces such that a minimal amount of metalsurface area is in contact with the artery wall. Focal elevatingelements placed at bridges between circumferential strut rings or at theapices of strut sections of the tack device can offer a majority ofarterial injury relief. When focal elevating elements are placed only atapices and bridges, the RMS of the strut members making up theconcentric ring changes a little while the RMS of the bridges is reducedmore significantly, due to the narrow length, offering relief ofrelative motion of the circumferentially oriented strut rings.

FIGS. 11 and 12 illustrate the use of focal elevating elements on a tackdevice of the type described above with respect to FIGS. 5A-C having twoor more concentric ring sections joined by bridges in between. FIG. 11shows a cell of two adjacent ring sections 290 a and 290 b with strutsections 290 c and which are joined in the middle by bridges 290 d. FIG.12 shows the ring sections expanded under expansion force and opposingsets of focal elevating elements 290 e deployed on opposite ends of thetwo adjacent ring sections 290 a and 290 b. An inset to the figure showsthe round elevating element having a height raised from the strutsurface.

FIGS. 13 and 14 illustrate a cell of another variant of focal elevatingelements formed on a tack device having two or more concentric ringsections 300 a, 300 b joined by bridges 300 d in between. In this cellvariant, the focal elevating elements 300 e are formed by bending thesections of the strut (illustrated as the strut apex) out of thecircumferential plane into varying degrees of tilt such as position “a”,or position “b”, up to a 90 degree vertical orientation shown inposition “c” to form the elevating element.

Inherent in the use of shape memory alloys for the tack devices is theability to conform to the shape of the blood vessel walls. Because thefocal elevating elements can exert an expansion pressure on the bloodvessel walls with a minimal risk of injury, they can be designed toreshape the blood vessel walls to a desired shape. FIG. 15 illustratesthe focal elevating elements (FEE) positioned in diametrically oppositepositions and formed with an extended height to reshape the artery wallsinto an ellipse cross-sectional shape which may better match thearterial cross section (such as an arterial branch) or expand the lumento be more open in plaque-free areas.

FIG. 16 shows a side view of FEEs spaced along a strut length having asmall area lifted off the arterial due to the height of the FEE liftinga short distance of the neighboring strut length. Outward forcesgenerated by the design or material used allow for only a small sectionon either side of the FEE to be lifted off the blood vessel wall.

FIG. 17 illustrates a perspective view of a series of FEEs spaced alonglength of a strut section of a tack device. FIG. 18 illustrates adetailed view of a cylindrically shaped FEE placed at the apex of astrut section of the tack device. FIG. 19 illustrates a perspective viewof a FEE formed as a pyramid shaped element at the apex of a strutsection. FIG. 20 illustrates a perspective view of a FEE formed as adome element at the apex of a strut section. FIG. 21 illustrates aperspective view of a FEE formed by bending the apex of a strut sectionupward. FIG. 22 illustrates a perspective view of a FEE formed bytwisting a strut section (made from wire).

Iv. Method and Devices for Delivering Plaque Tacks and FormingIntravascular Constructs in Situ

A variety of delivery methodologies and devices that can be used todeploy plaque tacks, some of which are described below. For example, aplaque tack can be delivered into the blood vessel with an endovascularinsertion. The delivery devices for the different embodiments of plaquetacks can be different or the same and can have features specificallydesigned to deliver the specific tack. The plaque tack and installationprocedure may be designed in a number of ways that share a commonmethodology of utilizing an expansion force of the delivery mechanism(such as balloon expansion) and/or the expansion force of a compressibleannular band to enable the tack to be moved into position in the bloodvessel, then released, unfolded or unplied to an expanded state withinthe blood vessel.

Referring back to FIGS. 4-4D, a delivery device or catheter 11 with anouter sheath 13 is shown in a pre-delivery state. Multiple plaque tacks10 can be compressed to be loaded onto the surface of the deliverydevice 11. The outer sheath 13 can then be advanced to cover the plaquetacks 10 in preparation for delivery. In some embodiments, the plaquetacks 10 are flash frozen in their compressed state to facilitateloading onto the delivery device. The tacks can extend in an array 10 xover a given length of the delivery device.

It can be seen that the plaque tack 10 can be positioned in a patient'svasculature at a treatment site by the delivery device 11. The outersheath 13 can be withdrawn or retracted to expose and release the plaquetack 10. The tack 10 can then be expanded in any suitable way, such asby being configured to self-expand or to be balloon expanded, asdiscussed herein.

Turning now to FIGS. 23-31B, a method of delivery of one or more tack10″ will be described. As has been mentioned, an angioplasty procedureor other type of procedure can be performed in a blood vessel 7. Theangioplasty may be performed on a diseased or obstructed portion of theblood vessel 7. The diseased vessel can first be accessed with acannula, and a guidewire 40 advanced through the cannula to the desiredlocation. As shown in FIG. 23, an angioplasty balloon catheter carryingballoon 42 is advanced over the guidewire 40 into a blood vessel 7 in alocation containing an obstruction formed by plaque. The balloon 42 isinflated at the desired location to compress the plaque and widen thevessel 7 (FIG. 24). The balloon 42 can then be deflated and removed.

While widening the vessel 7, a dissection 44 of the plaque may be causedby the angioplasty (FIG. 25). An angiogram can be performed after theangioplasty to visualize the vessel where the angioplasty was performedand determine if there is evidence of post-angioplasty dissection orsurface irregularity. A plaque tack or staple 10″ can then be used tosecure the plaque dissection 44 or other surface irregularity to thelumen wall 7 where needed.

A delivery catheter 11′ preloaded with one or more tacks 10″ can beadvanced through the cannula and along the guidewire 40 to the treatmentsite (FIG. 26). In some embodiments, a new or separate guidewire andcannula can be used. A distal most marker, either on the catheter or onthe distal most plaque tack, can be positioned under visualization atthe treatment location. An outer sheath 13′ can be withdrawn, exposing aportion of the plaque tack 10″. As has been discussed, the outer sheath13′ can be withdrawn until a set point and then the position of thecatheter within the vessel can be adjusted, if necessary, to ensureprecise placement of the plaque tack 10″ (FIG. 27). The set point can befor example, right before uncovering any of the tacks, uncovering aportion or all of a ring, uncovering a ring and an anchor, etc.

The tack 10″ can then be released in the desired location in the lumen.As discussed previously, simultaneous placement can result upon releaseof some embodiments of the plaque tack 10″. Additional plaque tacks 10″can then be placed as desired (FIG. 28) in a distal to proximalplacement within the treatment segment of the vessel.

In some embodiments, the precise placement of the plaque tack 10″ can beset upon positioning of the catheter within the vessel based on theposition of a marker. Once positioned, one or more tacks can then bedeployed while maintaining the catheter in place and slowly removing thesheath.

Upon placement of the second tack 10″, an intravascular construct isformed in situ. 11. The in situ placement can be in any suitable vessel,such as in any peripheral artery. The construct need not be limited tojust two tacks 10″. In fact, a plurality of at least three intravasculartacks 10″ (or any of the other tacks herein) can be provided in anintravascular construct formed in situ. In one embodiment each of theplurality of tacks has a length of no more than about 8 mm, e.g., about6 mm in an uncompressed state. In one configuration, at least one of,e.g., each of, the tacks are spaced apart from an adjacent tack by atleast about 4 mm, or between about 4 mm and 8 mm or between about 6 mmand 8 mm. Although certain embodiments have a length of 8 mm or less,other embodiments can be longer, e.g., up to about 15 mm long. Also,neighboring tacks 10′ be positioned as close as 2 mm apart, particularlyin vessels that are less prone to bending or other movements. In oneembodiment, each of the tacks has a relatively low radial force, e.g.,having a radial expansion force of no more than about 4 N, and in somecases about 1 N or less. In some embodiments, tacks can be configuredwith as little as 0.25 N radial force. In the various delivery devicesdescribed herein, the spacing between implanted tacks can be controlledto maintain a set or a minimum distance between each tack. As can beseen, the delivery devices and/or tacks can include features that helpmaintain the desired distance between tacks. Maintaining properinter-tack spacing can help ensure that the tacks are distributed over adesired length without contacting each other or bunching up in a certainregion of the treated vessel. This can help to prevent kinking of thevessel in which they are disposed.

While a three tack construct formed in situ may be suitable for certainindications, an intravascular construct having at least 5 intravasculartacks may be advantageous for treating loose plaque, vessel flaps,dissections or other maladies that are significantly more elongated (nonfocal). For example, while most dissections are focal (e.g., axiallyshort), a series of dissections may be considered and treated as a moreelongated malady.

In some cases, even shorter axial length tack can be used to treat evenmore spaced apart locations. For example, a plurality of tacks eachhaving a length of no more than about 7 mm can be placed in a vessel totreat a tackable malady. At least some of, e.g., each of, the tacks canbe spaced apart from an adjacent tack by at least about 5 mm. In somecases, it may be preferred to provide gaps between adjacent tacks thatcan range from about 6 mm to about 10 mm.

Optionally, once the plaque tacks 10″ are in place, the angioplastyballoon can be returned to the treatment site and inflated to expand theplaque tacks 10″ to the desired state of expansion. FIG. 29 shows theplaque tacks 10″ in their final implanted state.

Referring to FIGS. 29, 30A, and 30B, it can be seen how the focalelevating elements 32 can both penetrate the plaque in the blood vesselwall and also minimize the contact area of the plaque tack 10″ with theblood vessel wall. Similarly, FIGS. 29, 31A, and 31B illustrate thepenetration of the anchors 20. It can also be seen that the position ofthe anchors 20 on the bridge 14 allow the anchors to protrudetangentially from the circular shape formed by the plaque tack 10″. Thisbeneficially allows the anchors 20 to engage the plaque or vessel wallwhile also minimizing the overall amount of contact by the plaque tack10″, similar to the focal elevating elements 32.

A. Further Systems and Methods for Delivering Plaque Tacks

FIGS. 32A-48D illustrate system for delivering a vascular prosthesis,e.g., any of the endovascular staples or plaque tacks discussed above.FIG. 32A shows a system 100 for controlled delivery of a self-expandingtack. Other systems discussed below can be used to further enhancedeployed position of tacks and deployment of tacks that are expanded atleast in part by an outward radial force.

The system 100 includes a catheter assembly 104 and a fixture 108 withwhich the catheter assembly 104 can be coupled. The fixture 108 can havea small configuration to be hand-held, but in some embodiments is fixedto a larger object or otherwise configured to be immobilized. Thecatheter assembly 104 can be received within the fixture 108 and held inplace therein to limit or exclude unwanted relative motion between thefixture and at least one component of the catheter assembly 104. Forexample, the fixture 108 can include one or more caps 112 that can beconfigured to hold a portion of the catheter assembly 104. FIG. 32Ashows that in one embodiment, the fixture 108 includes proximal anddistal caps 112A, 112B which are discussed in greater detail below. Thecaps 112A, 112B can be removable to permit placement of the catheterassembly 104 into the fixture 108 by the clinician or can comepre-connected to the catheter assembly. The features of the fixture 108can be combined with or augmented by those of the figures of FIGS.46-48D, which describe additional details of deployment systems that canbe disposed at the proximal end.

The catheter assembly 104 includes an elongate body 132, a sheath 136,and a plurality of intravascular tacks 140. Although one tack 140 isshown in FIGS. 32B and 33B, a plurality of additional tacks can bedisposed within the catheter assembly 104, as discussed below inconnection with FIG. 36A.

FIGS. 36-36A show that the elongate body 132 has a proximal end 152, adistal end 156, and a plurality of delivery platforms 160 disposedadjacent the distal end. Each of the delivery platforms 160 comprises arecess 164 extending distally of an annular marker band 168 (FIGS. 33B &36A). The annular marker band 168 has a larger outer diameter ascompared to the recess 164. In some embodiments, the recess 164 can bedefined as the smaller diameter region next to, or between, one or twoannular marker bands 168 and/or an additional feature on the elongatebody 132. The platforms 160 are shown schematically in FIGS. 32A-33B andin more detail in FIG. 36A. In embodiments having a plurality of tacks140, a plurality of corresponding delivery platforms 160 are provided.Any number of tacks and platforms can be provided, e.g., four tacks andplatforms, two or more tacks and platforms, between 3 and 20 tacks andplatforms, or other configurations. Each delivery platform 160 caninclude at least one marker band 168. For example, a proximal markerband 168A and a distal marker band 168B can be provided to make the endsof the platform 160 visible using standard visualization techniques. Inthe illustrated embodiment, the proximal maker band 168A of a firstplatform 160 is also the distal marker band of the platform locatedimmediately distal.

The annular marker bands 168 can take any suitable form, for exampleincluding one more of tantalum, iridium, and platinum materials. In onespecific arrangement (see FIG. 36A), the proximal most marker band 168Acomprises tantalum, while distal marker bands 168B comprise one or moreof platinum and iridium. The use of different materials for radiopacitycan be based upon cost or a preference for higher visibility and/or athinner structure. Platinum/iridium provides a greater radiopacity thantantalum, permitting the distal marker bands to be thinner or morevisible than the tantalum band.

The ability to increase radiopacity to enable physician visibility underfluoroscopy can be provided for in various ways on the delivery deviceand the tack. One example is the inclusion of thicker zones of material(either wider circumferentially or radially thicker).

Also, the annular marker bands 168 have a radial height, which is theradial distance to the top of the band from the base of the recess 164.The radial distance can vary but preferably is just high enough toprevent the tack 140 from being caught between the elongate body 132 atthe annular marker band 168 and the sheath 136. In certain embodiments,the radial distance is about equal to at least the thickness of thetacks 140 disposed in the catheter assembly 104.

In another embodiment, the delivery platforms 160 are disposed distal ofa proximal marker band 168A′ where the marker bands are frusto-conicalsuch that the proximal end of each marker band has a radius nearly equalto the radius of the sheath 136 while the radius of the marker band atthe distal end is a reduced radius as shown in FIG. 36B. In someembodiments, the reduced radius can be the original radius of theelongate body 132 or recess 164 as discussed above. In other words, themarker band slopes upward proximally toward a next-most-proximal tack.This creates a wall 170 at the proximal end of the marker band 168A′. Adistal end of a tack sits against the wall and in this manner the markerband can assist in properly placing the tack. In addition, the slopedsurface can be useful to facilitate the smooth withdrawal of the sheathfrom the elongate body when the tack is delivered. For example, thesloped surface can limit the ability of the tack, pre-deployment, to gethung up on a marker band as the sheath is being retracted. In some casesthe tack may have a strut member that is not completely opposed to thewall, the sloped marker band can limit the ability of the marker band incatching this raised strut member as the sheath is withdrawn. In such anarrangement, the distal portion of the tack will be resting in thedelivery platform just proximal to the slope edge of the proximal markerband in the delivery system 100 as opposed to being right up against thewall of the un-sloped marker band.

In a different embodiment, the marker bands 168A″ can be frustoconicalin the opposite direction in which the radius is greatest near a distalend and slopes downward proximally, as shown in FIG. 36C. In thisembodiment, the marker band 168A″ has a wall 171 at the distal end. Thesloped surface can be useful to facilitate the smooth withdrawal of theelongate member after the tack has been delivered. For example, thesloped surface can limit the ability of the tack, post deployment, toget hung up on a marker band 168A″ as the elongate member is retractedfrom the vessel. In a variation, the delivery platform can befrustoconical in one or more directions.

The marker bands can be frustoconical in one or more directions. Thefrustoconical segment of the marker band can be formed by glue that cansecure the marker band onto the elongate member. The glue can form afillet between the marker band and the elongate member. The fillet canhave a concave, substantially planar or a convex outer surface. In someembodiments the marker band can have fillets on either side withdifferent outer surfaces. For example, the marker band can have aconcave fillet on the distal end and a fillet on the proximal end thathas a substantially planar outer surface or an outer surface that isless concave than the distal fillet.

In some variations, the tacks 140 are purely self-expanding. In othervariations, at least one of the delivery platforms 160 comprises anexpandable member to expand a tack disposed thereon. The expandablemember can comprise a standard construction as for balloon angioplastyor a specialized design, as in FIG. 45. The tacks 140 can also bedeployed by specialty balloons coated with drugs to minimize restenosis,inflammation, or other side effects of a treatment with a plaque tack.

The elongate body 132 includes a distal tip 172 that is tapered toprovide for easy insertion and a lumen 176 extending proximallytherefrom to the proximal end 152. As discussed above in connection withFIGS. 4-4D, and FIGS. 23-31, the lumen 176 can be used with a guidewireto guide the distal end of the catheter assembly 104 to a treatmentzone. The proximal end 152 can take any suitable form, but preferably isconfigured to lockingly engage with the fixture 108. For example, FIG.36 shows that the proximal end 152 can include a luer hub 178 withflanges that can be received within a similarly shaped recess formed inthe fixture 108. For example, a recess at least partly matching theshape of the hub 178 can be formed between a base 110 of the fixture 104and the cap 112A. When the elongate body is received in the fixture 104,the hub 178 is positioned between the cap 112A and the base 110 in thisrecess and is locked in place by a secure connection of the cap 112 tothe base 110, preventing unwanted movement of the elongate body 132relative to the sheath 136 and reducing or preventing movement relativeto a fixed reference frame, such as the reference frame of the fixture104.

The sheath 136 has a proximal end 192 (FIGS. 32A, 33A), a distal end 198(FIGS. 32B, 33B), and an elongate body 200 extending therebetween (FIG.33A). The sheath 136 is moveable relative to the elongate body 132 froma first position to a second position. The sheath can be formed of ahypotube, such as a metal or plastic hypotube. Flexibility and stiffnessof the sheath can be controlled by many features such as the slope andfrequency of a spiral cut along the length of the hypotube.

FIGS. 32A and B illustrate a first position or predeployment state ofthe catheter assembly 104 in which the distal end 198 of the sheath 136is disposed distally of a distal-most distal delivery platform 160. InFIG. 32B, the distal-most platform is occupied by a tack 140. Anotherplatform disposed immediately proximal of the occupied platform is shownwithout a tack for clarity but can be occupied by another tack. Furtherplatforms and tack can be disposed further proximally. FIGS. 33A-33Billustrate a second position or deployment state of the catheterassembly 104, in which the distal end 198 of the sheath 136 is disposedproximally of a portion of at least one delivery platform 160, therebyreleasing the tack 140.

The sheath 136 also can include a bifurcation luer 204 with a main armto receive the elongate body 132 and a side arm 206. The bifurcationluer 204 can be disposed at the proximal end of the sheath 136. The sidearm 206 includes a flushing port that is used to flush out air andincrease lubricity in the space between the sheath and the elongate body132. A tuohy borst adapter, hemostatic valve, or other sealingarrangement 208 can be provided proximal of the bifurcation luer 204 toreceive and seal the distal end of the elongate body 132 prior toapplication to a patient (e.g., in manufacturing). The tuohy borstadapter 208 can also provide a locking interface, such as a screw lock,to secure the relationship between the sheath 136 and the elongate body132. As shown in FIG. 32A, the tuohy borst adapter 208 can be locked tomaintain the relationship between the sheath 136 and the elongate body132 in the predeployment state. This can allow the physician to properlyplace the distal end without prematurely deploying the tack 140.

In some embodiments, a strain relieve sleeve 212 is provided between thebifurcation luer 204 and the elongate body 200 to make the connectionmore robust. The strain relieve sleeve 212 can be positioned on theopposite end of the bifurcation luer 204 from the tuohy borst adapter208. The strain relief sleeve 212 can take any form, such as being madeof polyolefin or other similar material.

In one technique of use, the distal end of the catheter assembly 104 isinserted into the patient and the proximal end is placed in the fixture108. The sheath 136 is in a distal position, e.g. with the bifurcationluer 204 forward in the fixture 108 (FIGS. 32A and B). During theprocedure, the sheath 136 is moved progressively towards a proximalposition, such as that shown in FIGS. 33A and B, with a proximal portionof the tuohy borst adapter 208 in contact with a distal portion of thecap 112A of the fixture 108. As the sheath 136 is moved proximally thetacks are deployed either one at a time or all at once. The cliniciansmay reposition the elongated body 132 after each deployment or each setof deployments, or one or more of the deployments may be done withoutrepositioning the elongate body 132. In some embodiments, markings 534can be located on the elongate body 132 to assist the clinician with theproper placement of the one or more tacks 140 as will be described inmore detail below.

The fixture 108 (FIGS. 32A and 33A) advantageously assists in placementof multiple tacks 140 to a treatment zone at spaced apart locations, asillustrated in FIG. 29. For example, the fixture 108 reduces unintendedrelative motion between the sheath 136 and the elongate body 132. If thefixture 108 is immobilized, the fixture assists in limiting motion ofthe elongate body 132 due to internal friction binding on the sheath 136as the bifurcation luer 204 is moved proximally. As a result, a morecontrolled deployment can result than if the clinician were to hold boththe proximal ends of the elongate body 132 and sheath 136 directly. Thishelps to ensure a minimum gap is provided in the treatment zone betweenthe distal end of a proximal tack and a proximal end of a distal tack.The gap can be seen in FIG. 29, which illustrated deployment of twotacks 10″. The gap advantageously minimizes the chance that two tackswill cause kinking in the vessel or other maladies due to being tooclose. The gap or spacing between tacks can be controlled to be betweenabout 4 mm and about 20 mm in certain embodiments. In other embodiments,the spacing between tacks can be controlled to be between about 5 mm andabout 14 mm. In other embodiments, the spacing between tacks can becontrolled to be between about 6 mm and about 12 mm, or about 6 mm andabout 8 mm. As has been mentioned, the tuohy borst adapter 208 can alsolock the sheath 136 in place on the elongate body 132 to secure thecatheter assembly 104 in the predeployment state (FIGS. 32A and B) andfurther prevent undesired movement. Applicants have found that theaccuracy of placement of multiple tacks in this manner to be within lessthan about 2 mm and in some instances has been less than about 1 mm fromthe target delivery site.

Also, this arrangement enables placement of two or more tacks withoutrequiring that the delivery platforms 160 be moved between deployment oftacks 140. Rather, the delivery platforms 160 can be positioned and heldin place prior to deployment of a first tack 140. After the deploymentof the first tack 140, the delivery platforms 160 can be maintained in aposition and the sheath 136 can be retracted to expose and deploy asecond tack 140, a third tack 140 or more.

The system 100 provides the further advantage of precise placement ofmultiple vascular prostheses once the catheter assembly 104 is placedinside the patient. In particular, after placement, the catheterassembly 104 need not be withdrawn and exchanged for other catheters orcatheter systems to perform further treatments. In this regard, thesystem 100 can be used for endovascular staples or tacks as well asstents and other vascular devices that are spaced apart in differenttreatment zones in the patient's body.

1. Minimizing Movement with a Distal Anchor

With certain endovascular prostheses, precise placement at a treatmentsite or zone is important, e.g., when the prosthesis is relativelyshort, such as having a ratio of axial length to transverse width (e.g.,diameter) of 1 or less or if placement occurs in a tortuous path (e.g.,at a arterial bend). Stabilizing at a proximal end, as with the fixture108, can provide reliable placement, but stabilizing closer to theprosthesis can provide even better accuracy in terms of axial locationas well as minimizing tilting of the device within the vessel. In thiscontext, tilting includes any non-perpendicularity of a transverseaspect of the device to the lumen in which it is deployed. For tack 10′,a transverse aspect can be defined by a plane intersecting the highoutward apices 24. Tilting in relatively short prostheses can reduce thestability thereof. Tilting of the tack 10′ can rotate the anchors 20 outof optimal orientation to engage plaque, reducing their effectiveness,for example.

a. Minimizing Movement with Actively Expandable Distal Anchor

FIGS. 37A and 37B illustrate a delivery system 100A that is a variationof the delivery device 100, but having a distal portion thereofconfigured to stabilize the system in the vasculature to enable evenmore precise placement of two or more tacks. In particular, the system100A includes a stabilization device 250 disposed on an outer surface ofthe system, e.g., on an outer surface of and elongate body 132A. Thestabilization device 250 can be adapted to directly engage a body lumen.In some embodiments, the stabilization device 250 is adapted to engagethe lumen at a plurality of locations disposed about the lumen, e.g., atdiscrete points or at a continuous circumferential line or area ofcontact. Such engagement can advantageously minimize movement of theelongate body 132A relative to the body lumen when relative movement isprovided between the sheath 136 and the elongate body 132A. For example,the stabilization device 250 can maximize radial centering duringmovement of the sheath 136, which can advantageously control a gapbetween adjacent tacks deployed by the system 100A.

The stabilization device 250 can maximize radial centering duringmovement of the sheath 136 to locate the center of the elongate body 132at the distal-most delivery platform 160 within about 50% of the radiusof the vessel in which the platform resides, which can advantageouslycontrol tilting of each tack deployed by the system 100A. In certainembodiment, the stabilization device 250 maintains the center of theelongate body 132 at the distal-most delivery platform 160 within about40% of the radius of the vessel in which the delivery platform resides.In other embodiment, the stabilization device 250 maintains the centerof the elongate body 132 at the distal-most delivery platform 160 withinabout 30%, about 20%, or about 15% of the radius of the vessel in whichthe delivery platform resides. Radial shifting can include transversedisplacement inside a body lumen or angulation within a vascularsegment. For example, due to the tortuosity or curvature of a bloodvessel, distal portion of the system 100A can have varying distance fromthe vessel wall along its distal length. When viewed from the side, theelongate body 200 of the sheath 136 forms an angle to the centrallongitudinal axis of the vessel. As a result, one side of the elongatebody 132A is closer to the vessel wall than the other and the distancevaries over the length of the tack 140. This can cause one of theproximal or distal ends of the tack 140 to engage the vessel first,causing the tack to tip in the vessel. The stabilization device 250 canbring a distal segment of the system 100A closer to coaxial with thelongitudinal axis of the vessel. For example, the stabilization devicecan be configured to maintain the longitudinal axis of the elongate body132A within 20 degrees of the longitudinal axis of the vessel for atleast 4 delivery platforms. In some embodiments, the stabilizationdevice 250 can be configured to maintain the longitudinal axis of theelongate body 132A within 10 degrees of the longitudinal axis of thevessel for at least 10 mm. In some embodiments, the stabilization device250 can be configured to maintain a transverse aspect of the tack 140 towithin 10 degrees of perpendicular to the longitudinal axis of the bloodvessel.

The stabilization device 250 can be configured to reduce or minimizeaxial shifting. For example the device 250 can reduce or minimizemovements of one or more of the delivery platforms 160 along the lumenof a vessel in which the platform is disposed to enhance control ofdeployment. The stabilization device 250 can maintain the axial positionof a distal facing surface of an annular marker band 168 to within about15%, 20%, 30%, 40%, or 50% of a delivery platform length. The deliveryplatform length can be measured parallel to the longitudinal axis of theelongate body 132 between a distal facing surface of a proximal markerband 168A disposed at the proximal end of the delivery platform and aproximal facing surface of a distal marker band 168B disposed at thedistal end of the same delivery platform. In some applications, axialshifting is reduced or minimized at least for second and subsequenttacks deployed, e.g., to help to maintain inter-tack spacing asdiscussed elsewhere herein. The stabilization device 250 can also beconfigured to reduce or minimize any offset in the position of a firstor subsequent tack that is deployed when compared to a plannedimplantation location. The planned implantation location is the absoluteposition in a vessel at which a clinician desires to place the tack,which can be based upon visualization techniques such as fluoscopy orother surgical planning method.

The stabilization device 250 can include an inflatable balloon 254 thatcan take any suitable shape. For example, the balloon 254 can becylindrical as shown in FIGS. 37A-37 or conical. One advantage of aconical shaped balloon is that the dilating function provided by thetapered tip 172 can be performed by the leading edge of the conicalballoon and so these structures can be combined in some embodiments. Or,if the anatomy is not cylindrical an appropriately shaped balloon, suchas a conical balloon, could be matched to the shape of the anatomy toprovide better apposition.

In the illustrated embodiment, a cylindrical balloon 254 is disposedproximally of the distal tip 172. The stabilization device 250 can bedisposed between the distal end of the elongate body 132A and at leastone of the delivery platforms 160. The balloon 254 is configured tominimize at least one of axial or radial shifting of at least one of thedelivery platforms 160 along or away from a longitudinal axis of a bloodvessel in which tacks or other vascular prostheses are to be deployed.

The balloon 254 can be inflated by any suitable means, such as byflowing an inflation medium through a lumen in the elongate body 132from the proximal end thereof to an inflation port in the balloon 254.The elongate body 132 for the system 100A can be formed as a dual lumenextrusion, where one lumen is used for the guide wire and the otherlumen is used to inflate the balloon 254. The inflation lumen can beconnectable at the proximal end of the elongate body 132 to a syringe orother source of positive pressure to deliver the inflation medium. Theballoon 254 has a low profile configuration prior to inflation thatenables it to reside on the elongate body 132 without impeding deliveryof the distal portion of the system 100A. For example, the balloon 254can be disposed within the sheath 136 (e.g., between an inner surface ofthe sheath 254 and the lumen 176) prior to being inflated. In anotherembodiment, the balloon is disposed longitudinally between the sheath136 and the tip 172. In such embodiment, it may be advantageous for theballoon to act as the tip where the distal end is tapered to allow fornavigation of the vessel while the proximal end of the balloon is thesame width (e.g., radius) as the sheath 136 to provide a smoothtransition between the two to prevent any step at the interface betweenthe balloon and the distal end of the sheath 136.

The use of the balloon 254 provides the clinician the ability toinitially place and inflate the balloon distally of the lesion. Thenafter the balloon is anchored to the wall of the vessel, the sheath 136is withdrawn exposing one or more tacks 140 enabling the tacks to bereleased at pre-defined separated locations. The separate locations arepre-defined because they correspond to the pre-established separationsof the tacks on the delivery system 100A.

One advantage of the balloon 254 is the additional functionality ofusing the balloon for post dilation of the tacks after placement. Inthis case after tacks are placed in the vessel the balloon 254 can berepositioned within a deployed tack 140 and reinflated engaging the tackwith outward pressure from the expanding balloon to enhance placement ofthe tack at the vessel wall.

FIG. 38 illustrates one of several embodiments where a proximal controlis provided to actuate a linkage to move one or more distal componentsof a delivery system to cause radial expansion for anchoring engagementwith a vessel wall. In particular, the system 100B includes astabilization device 250A that is configured to be actively enlargedfrom a low profile configuration to an expanded configuration. The lowprofile configuration is one that is suitable for advancement throughthe vasculature. The low profile configuration also enables the sheath136 to be advanced over the stabilization device 250A without radiallyexpanding the sheath 136.

The stabilization device 250A includes a stabilization element 270disposed adjacent the distal end of an elongate body 132A. The elongatebody 132B has a plurality of delivery platforms 160 proximal of thestabilization element 270 and is similar to the elongate body 132 exceptas set forth below. In the illustrated embodiment, the stabilizationelement 270 includes a plurality of elongate axially oriented strips 274that are separated by slots 278. The strips are sufficient flexible suchthat they are able to expand radially when compressive forces applied toproximal and distal ends thereof. The radial expansion of the strips 274causes outer surfaces thereof to engage the wall of the lumen atcircumferentially spaced apart locations.

The stabilization device 250A also includes a linkage 282 and anactuating mechanism configured to apply a compressive force to thestabilization element 270 (indicted by the arrows in FIG. 38). Thelinkage 282 can be a wire having a distal end coupled with the tip 172and a proximal end coupled with the actuating mechanism. The actuatingmechanism can be integrated into the deployment system 500 of FIG. 46,discussed in greater detail below, or any of the other deploymentsystems or devices described herein.

The linkage 282 can be eliminated by providing a balloon or otheractively expandable member within the stabilization element 270 suchthat the user can actuate the balloon to expand the elongate axiallyoriented strips 274 into engagement with a vessel wall. The strips 274advantageously define gaps therebetween through which at least someblood can flow downstream of the stabilizing element 270. This canminimize ischemia during a procedure compared to other anchor devicesthat are more occlusive.

An imaging device 286, such as a radiopaque band, can be positionedproximal of the stabilization element 270, e.g., between thestabilization element 270 and the distal most delivery platform 160, toindicate to the clinician that the stabilization element 270 is distalthe lesion or treatment zone.

b. Minimizing Movement with Passively Expandable Distal Anchor

Passive anchor elements can be used in addition or as an alternative toactively actuated anchors to provide stabilization of a delivery system.Passive anchor elements can be disposed on an outer surface of thedelivery system to minimize at least one of axial or radial shifting ofat least one of the delivery platforms.

The construction of FIG. 38 can also be used in a passive deploymentdistal anchor arrangement. For example, the stabilization element 270can comprise a shape-memory material. In one embodiment, the elongateaxially oriented strips 274 are formed from a shape-memory material andare configured to be in a radially enlarged state in the absence of acircumferential constraint. This variation is delivered adjacent to or alocation distal to a lesion or treatment zone in a constrainedcondition, e.g., with the sheath 136 over the elongate axially orientedstrips 274. Relative motion between the sheath 136 and the elongatemember 132B exposes the elongate axially oriented strips 274 and permitsthe strips to return to their radially expanded configuration. Thisembodiment advantageously eliminates the need for the linkage 282.

FIGS. 39-40 illustrate two passively deploying anchors that can be usedin a delivery system 100C. The delivery system 100C is the same as thedelivery system 100 except that with certain modifications to theelongate body 132. In particular, an elongate body 132C is provided thathas a self-expanding member 300 disposed thereon. In FIG. 39, theself-expanding member 300 includes a braided structure 304 that has aproximal and distal ends 308A, 308B connected to a portion of theelongate body 132C between the distal most delivery platform 160 and thedistal tip 172. The braided structure 304 can be delivered within thesheath 136 and deployed by providing relative movement between thesheath 136 and the elongate body 132C. The braided structure 304 has anexpanded width in the absence of any circumferential constraint that isgreater than the size of the vessel in which the system 100C is to bedeployed. As a result, the passive (or self-) expansion of the braidedstructure 304 creates an engagement with the vessel wall. Thereafter,one or more tacks 140 can be deployed in an accurate and controlledmanner.

The braided structure 304 provides the further advantage of permittingsome blood flow therethrough to maintain at least some perfusion oftissues downstream of the site of anchoring. With regard to other moreor fully occlusive anchors herein, lumens could be provided as analternative way to maintain perfusion. For example, if a balloon is usedto anchor a delivery system, a lumen through the balloon can be providedto perfuse downstream tissues. Perfusion may not be needed for rapidprocedures.

FIG. 40 illustrates the self-expanding member 300 as including aplurality of axially extending arms 320. Each arm 320 has a proximal end324 coupled with the elongate body 132D and a distal end 328. Theelongate body 132D is shown without the tip 172, but the tip can beprovided as in any of the embodiments above. Each of the arms 320 isconfigured to be held by the sheath 136 in a low profile configurationin which the distal end 328 of the arms 320 are adjacent to the elongatebody 132D and to extend radially away from the elongate body 132D whenthe sheath 136 is disposed proximally of the arms 320. In the expandedposition or configuration, as illustrated in FIG. 40, the distal ends ofthe arms are positioned to appose a body lumen. Any number of arms canbe provided. The arms 320 act similar to a tri-pod to stabilize andposition (e.g., centering) the elongate body 132D distal the deliveryplatforms 160.

FIG. 41 illustrates another form of passive anchoring, which involvesenhancing the isolation of the delivery system 100 from friction thatcan result from engagement of the system with the vasculature. Suchfriction greatly increases when the catheter assembly 104 traverses anytortuosity in the vasculature. One technique for isolating the system100 from friction is to provide a friction isolation sheath 340 to bedisposed between the sheath 136 and the vasculature. The frictionisolation sheath 340 can take any suitable form, but preferably isconfigured to prevent friction forces along the outer surface of thesheath 136 from causing unwanted movement of the elongate body 132during placement of the tacks 140.

One technique for isolating the sheath 136 from friction due totortuosity is to configure the friction isolation sheath 340 with alength sufficient to extend from a vascular access site A, such as afemoral artery, to a treatment zone. FIG. 41 illustrates that thetreatment zone Z can be across the iliac bifurcation B and in or distalof the iliac artery of the leg through which vascular access was notprovided. In other words, the distal end 344 of the friction isolationsheath 340 is disposed beyond the bifurcation B or other tortuosity T.Other treatment zones can be reached using the friction isolation sheath340. The length could be sufficient to extend distally of any additionaltortuosity below the iliac artery in the access or non-access leg. Inother words, the distal end 344 of the friction isolation sheath 340 isdisposed beyond the arch or other tortuosity. In some techniques thefriction isolation sheath could be configure with enhanced lubricity onan inside surface thereof. The enhanced lubricity would reduce frictionforces below a threshold to eliminate unwanted movement of the elongatebody 132 due to such friction.

2. Structures and Methods for Maintaining Spacing

Tacks and other vascular devices that benefit from maintaining apre-determined minimum spacing can be deployed with the system 100, asdiscussed above. For example, once stabilized, e.g., by any of thetechniques described herein, minimum spacing can be provided by avariety of structures. For example, the delivery platforms 160 canassist in managing device spacing as desired. In some embodiments, theproximal marker bands 168 each project radially away from the elongatebody 132 by an amount sufficient to present a distal-facing shoulderthat can abut a tack 140 disposed on the delivery platform 160. Theshoulder can function like a plunger providing a holding or pushingforce against a proximal aspect of the tack 140. This holding or pushingforce can prevent proximal migration of the tack 140 as the sheath 136is being moved proximally relative to the elongate body 132.

FIG. 42 illustrates other embodiments in which a delivery system 400 isprovided that is adapted for delivering a vascular prosthesis thatincludes a plurality of discrete devices. The system 400 includes anelongate body 404, an elongate packet 408, and a sheath 412. Theelongate body 404 includes a distal end 414, a proximal end (not shown),and a plunger 416 disposed adjacent the distal end 414. The elongatepacket 408 has a plurality of intravascular tacks 140 coupled therewith.The tacks 140 are disposed along the length of the elongate packet 408.

The sheath 412 has a proximal end (not shown) and a distal end 420 andcan be positioned in a first position in which the distal end 420 of thesheath 412 is disposed distally of at least a portion of the elongatepacket 408. The first position can be one in which the entirety of thepacket 408 is disposed inside the sheath 412. For example, the distalend 424 of the packet 408 can be disposed inside and at or proximal ofthe distal end of the sheath 412. The sheath 412 can be positioned in asecond position in which the distal end 420 of the sheath 412 isdisposed proximally of the elongate packet 408. The second position canbe achieved from the first position by proximal motion of the sheath 412relative to the plunger 416, by distal motion of the plunger 416relative to the sheath 412, or by simultaneous proximal motion of thesheath 420 and distal motion of the plunger 416. The plunger is moved orheld stationary by applying a force to the proximal end of the elongatebody 404.

The elongate packet 408 is configured to maintain a minimum spacingbetween adjacent tacks during deployment, e.g., during any form ofmovement of components of the system 400, such as those discussed above.The elongate packet 408 is also configured to permit expansion from acompressed configuration in which the elongate packet 408 is received inthe sheath 412. In an expanded state, the elongate packet 408 can engagea vessel wall.

In various embodiments, the elongate packet 408 can be configured torelease the tacks to expand toward a vessel wall after deployment. Thepacket 408 can be configured with an elongate sleeve 428 and a rip cord432. The rip cord 432 preferably is coupled with the sleeve 428 suchthat separation of the rip cord 432 from the sleeve 428 permits thetacks 140 to expand toward a vessel wall. FIG. 43 illustrates anembodiment of the sleeve 428 that comprises a woven structure 436, whichcan have a high weave angle. For example, weave angles of at least about110 degrees could be used. In this embodiment, the rip cord 432 can beconfigured as one or a plurality of unraveling strings. The rip cord 432can be actuated to release the constraining force of the sleeve 428. Forexample, in the woven embodiments the rip cord 432 causes the sleeve tounravel so that the tacks 140 are released.

The rip cord 432 preferably would have a proximal portion coupled withan actuator at the proximal end of the corresponding delivery device.The rip cord 432 could run through a lumen (e.g., a dedicated lumen)within the delivery system and be actuatable separately from a sheath orplunger, if provided. The clinician would use such an actuator to applya force to the rip cord 432 causing the woven structure to unravel orotherwise deploy the tacks 140.

Another embodiment can be provided in which the rip cord is eliminated.For example, the sleeve 428 can comprise a structure that weakens onceimmersed in blood so that shortly after deployment it passively releasesthe tacks 140. The sleeve 428 could comprise a bioabsorbable material ora non-reactive polymer that is left between the tacks 140 and thevasculature. The entire deployed structure, including the tacks 140 andsleeve 428 could be configured to absorb into the vasculature and toeventually disappear in the patient in certain applications. In otherembodiments, the elongated packet 408 can be coated with drug elution,e.g., with the rip cord 432 bioabsorbable and the sleeve 428 remainingwith the tacks to elute. As the rip cord 432 is absorbed the remainingpacket 408 is pressed against the vessel wall by the expanding tacks andremains. In this alternative, the rip cord 432 can just be a region of(or one or e plurality of strands of) the woven structure 436 and not anotherwise distinct structure from the structure 436.

In an embodiment of FIG. 44, the elongate packet 408 includes aplurality of tacks 140 and a member 440 that extends axially through acentral zone of each of the tacks. The member 440 is coupled with eachof the tacks 140 to restrain the tacks in a low profile configuration,in which the tack can be disposed in the sheath 136. FIG. 44 shows aplurality of tacks 140 after being separated from the elongate member440 and after expanding into engagement with the wall of the vessel V.The elongate member 440 can be connected to the tacks 140 in anysuitable fashion, such as by employing one or a plurality of radiallyextending member 448. The members 448 are configured to restrainexpansion of the tacks 140 while the task are disposed in this sheath136 but to break after being deployed therefrom. The breaking of theradial members 448 can be accomplished by any active mechanism, such asby cutting, untying, or actuating a rip cord, or by a passive mechanism,such as by eroding in the vasculature. After the radial member 448separate from the tacks 140 the tacks can move away from the member 448into a radially expanded configuration, providing a gap between themembers 448 and the tacks 140.

The member 440 can then be moved out of the sheath 136 by providingrelative motion between the member 404 and the sheath 136. In theillustrated embodiment, the distal end of the elongate member 404 isconnected to the proximal end of the member 440 and acts as a plunger topush the packet 408 out of the sheath 136. In other embodiments, theelongate member 404 has a distal end that is small to be insertedthrough the tacks 140 when the tacks are in the low profileconfiguration. The elongate member 404 can be coupled with the distalend of the member 440 of the elongate packet 408. In this arrangement,the elongate member 404 acts on the distal end of the packet 408 ratherthan on the proximal end as in the embodiments of FIGS. 42-43.

In each of the embodiments of FIGS. 42-44, a pre-defined andsubstantially fixed axial spacing is maintained between adjacent tacks.Thus, the elongate packet provides a device spacing element capable ofproviding accurate separation between tacks during placement. Thisprovides advantages such as minimizing vessel kinking, excessive metaland other issues associated with positioning tacks 140 and othervascular prostheses too close together.

3. Balloon Expansion

A balloon can also be used to deploy a plurality of tacks in acontrolled fashion to have the correct spacing therebetween. FIG. 45illustrates a deployment system balloon 490 having a tack 140 crimpedthereon. The illustrated portion of the tack 140 is one of a pluralityof repeating segments, which have mirror image counter-parts asdiscussed above, the other segments being omitted for clarity. Theballoon 490 is for delivering and expanding the tack 140 and may bereferred to as a carrier balloon. The balloon 490 can be shaped or cancomprise more than one plasticity offering controlled inflation. Thetack 140 and the balloon 490 are carried to the site of repair inside asheath (not shown, but analogous to those discussed above). Duringdeployment the balloon 490 is expanded as or after it leaves the distalend of the sheath. The expansion of the balloon 490 expands the tack140. In one variation of this system, the balloon is used to deploy atack 140 that can be non self-expanding or partly self-expanding. Forexample, the balloon 490 can be expanded to a threshold where it breaksa constraining structure disposed between the tack 140 and a sheath. Thebreaking of the retaining structure permits the tack 140 to expand. Theballoon 490 can entirely expand the tack 140 (and using protrusions inthe balloon 494, discussed more below, can raise regions of the tack formore effective anchoring), release the tack 140 to self-expand, orprovide some combination of balloon and self-expansion.

Another technique for controlled placement of a tack 140 is to expandthe tack under radially outwardly directed pressure, such as byexpansion of a balloon. FIG. 45 illustrates the balloon 490 in anexpanded state having a plaque tack 140 disposed thereon. Although asingle balloon is shown, in one embodiment a balloon is incorporatedinto each of the delivery platforms 160 of the delivery system 100. Theballoon 490 can take any suitable configuration, but preferably isconfigured to rotate anchors of the tack 140 into a plaque or othervascular anomaly to be held up against a vessel wall. For example, theballoon 490 can comprise a radial protrusion zone 494 disposed in anexpandable section thereof. The radial protrusion zone 494 is preferablyconfigured to rotate the anchor 20 of the tack 140 (see anchors 20 inFIG. 5C) outward of a cylindrical plane containing proximal and distalportions of the tack.

The protrusion zone 494 can have any suitable configuration, such as aplurality of discrete protrusions disposed circumferentially about theballoon 490. The protrusions can be positioned to be beneath the anchors20 of the tacks 140, but to not extend entirely under the markers 22.The protrusions can be configured such that as the balloon 490 expands,the protrusions expand by a greater amount so that the tack 140 can bedeformed from a generally cylindrical delivery shape to an arrangementwhere the bridges 14 rotate about an axis connecting the end points ofthe bridges. This rotation causes the anchors 20 to be tilted away fromthe center of the blood vessel and into the plaque to be tacked.

In other embodiments, the protrusion zone 494 can be a substantiallycontinuous circumferential structure, such as a ridge that extends allthe way around the balloon. Preferably in this arrangement, there isstill a greater radial protrusion of the balloon in the expanded statein the location disposed radially between the anchors 20 and thelongitudinal axis of the balloon.

The protrusion zone 494 is preferably at least about 0.05 mm in height.In other words, the protrusion zone 494 has a radially outermost tip orportion that is at least about 0.05 mm away from the average surface ofthe balloon 490 when the balloon is expanded to the diameter of thevessel in which the tack is to be placed. Or, if a plurality ofprotrusions is provided, a cylinder intersecting the tips of all theprotrusions is preferably radially larger than the average radius of theballoon by about 0.05 mm. In other embodiments, the protrusion zone 494is between about 0.05 mm and about 0.4 mm in height. While in otherembodiments, the protrusion zone 494 is between about 0.07 mm and about0.4 mm in height. Still further embodiments provide the protrusion zone494 is between about 0.1 mm and about 0.2 mm in height. The balloon 490can advantageously be paired with a tack that is not self-expanding.Standard deformable stent materials can be used, such as stainlesssteel. In some cases, it may be advantageous to combine a balloonexpansion step with a self-expanding device. Thus, the balloon 490 canalso be used in combination with self-expanding tacks. The additionalheight of the protrusion zone 494 can advantageously engage a feature ofa tack 140 (such as an anchor 20 or a bridge 14) to prevent the tackfrom sliding along the axis of the balloon. In a typical balloon, alength that is not surrounded by a prosthesis will expand more than alength that is surrounded by a prosthesis, causing a “dog bone” shapewhen expanded. A dog bone shape balloon could induce unwanted movementof tacks mounted thereon. The protrusion zone 494 can prevent thismovement by engaging the tack, as discussed above. The balloon 490 canbe configured to elute a drug that is beneficial in a treatment, such asone that helps to minimize restenosis or inflammatory response.

A balloon 490 can also include a number of constraints, such asconstraining bands 492, which limit expansion of the balloon to certainareas of the balloon as shown in FIG. 45A. For example, the balloon 490can be used with a series of non-self-expanding tacks 140 spaced alongthe length of the balloon 490. FIG. 45A illustrates one section of sucha balloon. As balloons can have a tendency to expand from one end, theconstraining bands can limit this type of expansion and focus expansionat each region that includes a tack 140. Segments 494 of the balloonthat do not include a tack or a constraining band can be used to ensureproper spacing between the tacks and can form a barrier betweensuccessive tacks as the balloon expands to its fully expanded position.

4. Deployment Systems

As discussed above in connection with FIGS. 4A, 32A, and 33A, a varietyof tools and components can be provided for the proximal end of thedelivery system 100. FIGS. 46-48D illustrate addition details of theseand other embodiments of a deployment system 500 for the delivery system100. The deployment system 500 preferably includes a housing 504 thatcan be held by the user and that includes a trigger device 508. Thehousing 504 is connected to the proximal end of the catheter assembly104, e.g., is connected to the elongate body 132 and the sheath 136 (seeFIG. 34) to impart relative motion between these two components. Incertain embodiments, it is preferred that the elongate body 132 bestationary and the sheath 136 be retracted to provide relative motion.But under other circumstances, this can be reversed so that the elongatebody 132 is caused to move while the sheath 136 is stationary.

In one arrangement, the housing and trigger 504, 508 comprise a singledeployment ratchet handle arrangement that is manually powered. In thisarrangement, each time the trigger 508 is activated, relative proximalmovement of the sheath 136 would uncover one prosthesis (e.g., tack140). The trigger 508 preferably would be spring loaded such that afterbeing depressed it would spring back to an original position.

a. Power Assisted Deployment Devices

As discussed above, a variety of indications are advantageously treatedwith a plurality of discrete prostheses. For some treatments, thelocation of the treatment is remote from the location where the deliverysystem enters the vasculature or body lumen system. Both of theseconditions can increase the amount of force needed to actuate thetrigger 508. For such conditions and also to make deployment easier, thedeployment system can include a mechanical energy source 516 to generatea force needed to provide relative movement of the sheath 136 relativeto the elongate body 132. The energy source 516 can be configured togenerate about the same force at the distal end of the system 100 fordeployment of one tack 140 or for deployment of a plurality of tacks140. The energy source 516 can be configured to generate a force that isconstant over a stroke length that is more than two times the axiallength of the tacks disposed in the system 100. In some embodiments, theenergy source 516 is configured to maintain about the same rate ofrelative movement (e.g., sheath retraction) at the location of adistally located tack and a proximally located tack.

The energy source 516 can incorporate a variety of components and toimpart energy or power to the system. For example in one embodiment, theenergy source 516 comprises a gas cylinder that offers a controlledretraction of the sheath the required distance. The energy source 516could be external to the housing 504, as illustrated in FIG. 47, forexample, including a fluid passage connected to an external tank of gas.In one variant, the gas is contained within the housing 504 in a smallvessel offering the required energy. In these embodiments, the system isnot under any strain until the gas source is engaged

To induce retraction of the sheath 136 relative to the elongate body 132and marker 168, a proximal plunger 520 is coupled with the sheath 136.The plunger 520 also is arranged within the housing 504 to form aportion of an enclosed space that is in fluid communication with the gasof the energy source 516. The deployment system 500 is configured suchthat as a bolus of gas is delivered into this enclosed space, theplunger 520 moves proximally within the housing 504. The proximalmovement produces corresponding proximal movement of the sheath 136.

The energy source 516 need not be limited to a gas cylinder. In anotherembodiment, a compression spring is provided that is adapted to producea substantially constant force. Preferably the spring is arranged toprovide sufficient force over a longitudinal length that is sufficientto uncover as many prostheses, e.g., tacks 140, as are desired for thetreatment. This distance or stroke length can be between about 10 mm andabout 200 mm (e.g., for a system carrying or operated to deploy up to 20tacks). In certain embodiments, the stroke length is between about 8 mmand about 80 mm (e.g., for a system carrying or operated to deploy up to10 tacks). In other embodiments, the stroke length is between about 7 mmand about 10 mm (e.g., for a system carrying or operated to deploy 1tack). In one arrangement, the spring is tensioned prior to retractionof the sheath 136. In another embodiment, the spring is tensioned priorto use by the clinician (e.g., at the factory).

As discussed further below, it may be desirable to be able to select thenumber of devices to be deployed. In such circumstances, the deploymentsystem 500 can be configured such that only a portion of the stroke ofthe spring is engaged. When selecting number of tacks to be deployed,the handle would automatically engage the correct length of spring andhence would supply the adequate amount of force. As discussed below inSECTION IV(A)(4)(b), a selector can be included to enable the clinicianto choose a series of tacks 140 to be deployed, e.g., a subset of thefull number of tacks on the delivery system to be deployed in a givendeployment event.

A spring-like force can be generated by compressing gas as well. Forexample, a structure analogous to the plunger 520 could be urged andheld distally within the handle and only released once deployment is tooccur. The compressed gas would cause the plunger to be displacedproximally, along with the sheath. This effect may be considered as aform of spring recoil.

Another spring arrangement that could be employed comprises a bellowsspring, which would be advantageous in designs where a longer motion isrequired to retract the sheath. In this arrangement the energy source516 is adapted to act across two point of the bellows spring. The energysource could include a gas or liquid under pressure acting on one end ofthe bellow to actuate the motion of the bellow. As the energy spring isallowed to recoil the distance the bellow retracts is a multiplier ofthe distance travelled by the energy source spring. This system offers aconversion between a high force spring and a controlled long distancelow force retraction.

Another option would be to employ a rotary spring driving lead screw.The spring could be pre-tensioned and connected to a lead screw. Thesheath 136 would then be connected to a follower that moves as the leadscrew rotates. This would allow the rotary motion provided by the springto be converted, with adequate strength through the lead screw, toproximal (linear) movement of the sheath.

b. Selector for Multi-Prosthesis Deployment

An elongated treatment zone, which can comprise, for example, plaque oran elongate vessel flap, may be treated with a plurality of tacks 140.In certain procedures, it is possible through visualization or othersurgical planning tool to know the number of tacks or prostheses neededto provide sufficient treatment. For such procedures, the deploymentsystem 500 can include a selector 532 to determine the number ofprostheses or tacks to be deployed, as illustrated in FIG. 48A. In oneform, the selector 532 can include markings 534 on one or more of theelongate body 132 and the sheath 136. These markings can give a visualcue to the clinician holding the handle 11F, the fixture 108, or thehousing 504 of how many tack have been deployed.

FIG. 32A shows the markings 534 disposed on a proximal portion of theelongate body 132. In this embodiment, the tuohy borst adapter 208 canserve as the selector. Proximal movement of the sheath 136 can cause thetuohy borst adapter 208 to pass each of a plurality of the markings 534.Each time the tuohy borst adapter 208 passes a marking 534, a tack 140is exposed and can be deployed. Thus, the user can know how many tacks140 are deployed, as well as, how many are left to be deployed byobserving the position of the tuohy borst adapter 208 relative to theplurality of markings 534. The number of markings 534 that are exposedand not covered by the tuohy borst adapter 208 can indicate the numberof tacks 140 left to be deployed.

In some embodiments, the length of the sheath 136 can be correlated tothe position of the markings 534 on the elongate body 132, as well as,the position of the delivery platforms 160. For example, the sheath 136can be sized such that movement of the sheath from a first marking 534to a second marking 534 can expose one delivery platform 160, or asubstantial part of a delivery platform. In some embodiments, thedelivery platform, including the distal marker band can have a length L1that can correspond to the length L2 from the distal end of a firstmarking to the distal end of a second marking. In some embodiments, themarker bands 168 can be spaced apart a distance that is the samedistance spacing apart the markings 534. In some embodiments, themarkings 534 can be spaced apart a distance greater than the distancebetween the marker bands 168 or the space can be maintained while thesize of the markings 534 progressively increases. In this way the spacebetween markings, or the markings 534 themselves can accommodate fordifferences in the elasticity of the sheath 136 and the elongate body132 and/or friction between the sheath and its environment within thevessel, which may cause the distal end of the sheath to experience lessmovement than the proximal end. In some embodiments, the space betweendistal ends of markers 534 can steadily increase from the first twodistal most markers 534 and the following proximally spaced markers 534.

In some embodiments, the markers 534 are distinct tick marks. In otherembodiments, the markers 534 can be distinct regions, such as differentcolored regions. Another way to accommodate for the elasticity of thesheath is to indicate with the markings 534 that deployment of a tack140 will occur when the proximal end of the sheath is within the regionor between the tick marks. The distance between delivery platforms 160and the size of the marker bands 168 can be configured with the markers534 to accommodate the anticipated elasticity of the sheath 136.

FIG. 4A shows that the markings can also be placed on the handle 11F. Inparticular, the handle 11F is provided with a series of markings 534that indicate how far the sheath 13 has moved. Each time the actuator11G moves past a marking 534, another tack 140 is moved out of thesheath 13 and can be deployed.

In certain embodiments, it is preferred that the selector 532 beconfigured to prevent conditions that would permit deployment of morethan a selected number of tacks 140. In these embodiments, the selector532 also includes a limiter 536 that prevents deployment of more than apre-selected number of tacks. FIG. 48A shows that in one embodiment, thelimiter 536 includes a slideable stop 538 that can be disposed about aproximal portion of the elongate member 132. A locking device, such as athumb screw, is provided for immobilizing the limiter 536 on theelongate member 132. A viewable window 540 in the limiter 536 displaysindicia of how many tacks will be been deployed if the sheath 136 ismoved proximally into contact with the stop 538, how many remain in thesystem or some other useful indicator of the status of the deployment.In this case, if the limiter 536 is disposed on a proximal portion ofthe elongate body 132 indicating “1”. This informs the clinician thatwhen the sheath 136 sheath contacts the stop 538, one tack will bedeployed.

FIG. 48B illustrates another variation in which relative rotation of aproximal portion of the sleeve 136 and a selector 560 disposed withinthe housing 504 can enable the user to select the number of prostheses(e.g., tacks 140) to be deployed. In one variation the selector 560includes a rod 564 that extends into the lumen formed in the sheath 136.The rod includes a pin or other radial protrusion 568 that extendsoutwardly into one of a plurality of notches 572 disposed on the innersurface of the sheath 136. The notches include proximal facing surfaces576. Each notch 572 in the counter-clockwise direction as seen in thefigure is progressively farther from the proximal end of the sheath 136.Each progressively farther notch 572 permits an additional increment ofaxial movement of the sheath 136 relative to the pin 568. Each incrementof axial movement corresponding to the amount of movement needed at thedistal end to expose a delivery platform 160 and corresponding tack 140.By rotating the sheath 136 relative to the pin from the positionillustrated according to the arrow A, a greater number tacks can bedeployed in a single stroke. Relative rotation can be provided bycoupling the rod 564 with a dial and an indicator disposed on theoutside of the housing 504.

In one variation of the embodiment of FIG. 48B, the selector 560 can beconfigured as a sleeve disposed around the sheath 136. The sheath 136can be modified to include an outwardly protruding pin similar to thepin 568 and the sleeve can be modified to have notches. In thisarrangement, the structure in FIG. 48 labeled “564” is a sheath and thestructure labeled “136” is the sleeve disposed about the sheath.

FIG. 48C illustrates a deployment system 600 that can be disposed ahousing similar to that illustrated in FIG. 46. The system includes botha mechanical energy source and a selector for selecting the number oftacks to be deployed. The system includes an actuator 604 coupled by acable 608 to an energy storing device 612. The actuator 604 is mountedon a rigid body 610 that is also coupled with the elongate body 132. Theenergy storing device 612 can include a rotary spring driving a leadscrew. More specifically, the cable 608 is wound around a barrel 610that can rotate about the axis of a base screw 614. A spring is coupledwith the barrel 610 such that as the barrel rotates to unwind the cable608, the spring is loaded and after the tension is removed from thecable, the spring causes the barrel to rotate in the opposite direction,winding the cable back onto the barrel. The length of the cable 608wound on the barrel is equal to or greater than the linear distance fromthe distal end of the distal most delivery platform 160 to the proximalend of the proximal-most delivery platform 160. The selector includes aplurality of stops 620 that are disposed proximal of the sheath 136. Thestops can be activated or deactivated. A first stop 620A is locatedclosest to the distal end of the sheath 136 and permits movement of thesheath by an amount sufficient to only deploy one tack 140. After thefirst tack has been deployed, the first stop 620A can be deactivated bybeing depressed into the rigid body 606 and a second stop 620B can beactivated. The second stop permits travel of the sheath 136 a distancesufficient to expose the second-most distal delivery platform 160 andtack 140. After the second tack has been deployed, the second stop 620Bcan be deactivated by being depressed into the rigid body 606 and athird stop 620C can be activated. The third stop permits travel of thesheath 136 a distance sufficient to expose the third-most distaldelivery platform 160 and tack 140. After the third tack has beendeployed, the third stop 620C can be deactivated by being depressed intothe rigid body 606 and a fourth stop 620D can be activated. The fourthstop permits travel of the sheath 136 a distance sufficient to exposethe fourth-most distal delivery platform 160 and tack 140. If more thanfour tacks and platforms are provided, additional stops 620 can beprovided. The energy stored in the energy storing device 612 causes theactuator 604 to be automatically returned to the home position forfurther triggering.

FIG. 48D illustrated another concept that could be used for a deploymentsequence where only one tack at a time is deployed. This arrangement issimilar to a bolt-action mechanism. The deployment system includes aselector device 660 that has a plurality of tines 664 spaced out axiallyalong a rigid body 666. The tines 664 provide a rigid stop structure. Amoveable member 668 coupled with a proximal portion of sheath 136 can bedisposed between adjacent tines 664, e.g., distal of the “2” tine 664,between the “2” and “3” tines, etc. The moveable member 668 could bedisposed proximal of but adjacent to the “2” tine prior to deployment ofa tack 140. An energy source driven actuator could be triggered, afterwhich the sheath 136 and the moveable member 668 coupled thereto willslide proximally. The moveable member 668 will slide into contact withthe “3” tine. This provides a hard stop and may be useful if relativelyhigh power energy source is used. To deploy additional tacks, themoveable member 668 would be sequentially moved to the “4”, “5”, and “6”tines.

5. Shuttle Deployment Device

A shuttle deployment device 700 as shown in FIG. 49 can have one or moredelivery platforms 160. The delivery platform 160 can include a markerband 168 at one or both ends thereof, as discussed above. A set ofrails, fingers, or tines 702 can extend from one end of each marker band168. In the illustrated embodiment there are 4 rails 702, though agreater or lesser number can be used. The rails 702 extend distally froma proximal marker band 168A. In another embodiment, the rails 702 extendproximally from a distal marker band 168B. The proximal and distalmarker bands 168A, 168B are shown in FIG. 36A and can be proximal anddistal sections of a single band or separate bands that are axiallyspaced apart. Also, only one set of rails 702 is illustrated. However,it is to be understood that in other embodiments, a set of rails 702 canbe provided for each delivery platform 160. The rails 702 can have acompressed position, such as when they are within the sheath 136, and anexpanded position where they are unrestrained. In the expanded positionthe rails can have be curved, flared, angled, or otherwise configuredsuch that the shuttle 700 has a reduced dimension transverse to thelongitudinal axis of the elongate member 132 proximally along itslength.

As the sheath 136 is retracted, the rails move radially outwards towardsthe vascular wall to the expanded position as shown. This can center thecatheter and establish a type of ramp or gradual increase in diameter toguide the positioning and expansion of the tack 140. As the tack 140expands, it can slide down the rails into position in the vascular wall.The radial expansion of the tack 140 is thereby controlled as the strutsare limited to the amount of expansion by the radial rails. The tacks140 may be crimped around the rails 702 or may be crimped with somerails inside the tack 140 and some rails around the rails.

The shuttle device 700 can be disposed at the distal end of the elongatebody 132. As illustrated, the shuttle device 700 has a plurality of gapsbetween the plurality of rails 702. These gaps can be used to assist inthe proper positioning of the tack 140. For example, anchors, markersand/or other features of the tack 140 can project radially through thegap, such that a portion of the tack is radially between the rails andthe longititudal axis of the elongate member and another portionprotrudes to a radial position circumferentially between (or beyond)adjacent rails. In this position, at least a portion of the rail can beconsidered to be disposed radially between a portion of the tack and thelongitudinal axis of the elongate member 132.

This configuration can provide many benefits such as preventing rotationand providing addition control of the placement of the tack 140 in thevasculature. The gaps can also permit anchor portions of the tackanchors 20 to connect to the vasculature at the distal end of theshuttle device 700 or rail 702.

In some embodiments, the rails 702 of the shuttle are biased to theclosed position. At the same time, the tack 140 can be a self-expandingtack that biased to move to its expanded configuration. When theself-expanding tack is loaded into the shuttle these two opposed biasescreate stored energy within the shuttle once the sheath is in place andthe two are confined in position. The bias of the tack can be greaterthan the bias of the rails such that the tendency to collapse isslightly less then the energy of the tacks to expand. Thus, once thesheath has been retracted from the delivery platform 160, thecounteracting forces can provide a controlled expansion as the tacksleaves the distal end of the delivery catheter. This can advantageouslyreduce or eliminate too rapid expansion of the tack 140, which canresult in unpredictable or placement.

Use of Plaque Tack after Drug Eluting Balloon Angioplasty

The use of plaque tack devices can be combined with use of drug elutingballoon (DEB) angioplasty to manage post angioplasty dissection andavoid the need for stents. In DEB angioplasty, a drug-eluting balloon ora drug coated balloon is prepared in a conventional manner. The drug maybe one, or a combination, of biologically active agents that are usedfor various functions, such as anti-thrombotic, anti-mitotic,anti-proliferative, anti-inflammatory, stimulative of healing, or otherfunctions. The DEB is delivered on a guidewire across an area ofblockage or narrowing in the blood vessel system. The DEB is inflated toa specific pressure and for a period of time consistent with themanufactures guidelines of use for treatment purposes, as it pertainsthe drug coating and the intended outcomes, then the DEB is deflated andremoved. At this stage the medication from the DEB has been transferredto the wall of the blood vessel. Intravascular imaging by ultrasound isthen used to assess the integrity of the artery and the smoothness ofthe blood vessel surface at the site where the balloon was inflated. Thepresence of damage along the surface may be indicated as dissection,elevation of plaque, disruption of tissue, irregularity of surface. Theplaque tack is used to tack down the damaged, disrupted, dissected, orirregular blood vessel surface. This permits continuation of a“stent-free” environment even if damage to the blood vessel has occurredas a result of balloon angioplasty.

At this stage the medication from the DEB has been transferred to thewall of the blood vessel. Contrast is administered into the blood vesselunder fluoroscopic guidance or another method such as intravascularultrasound is used to assess the integrity of the artery and thesmoothness of the blood vessel surface at the site where the balloon wasinflated. In some cases, one or more of these completion studies willdemonstrate the presence of damage along the surface at the site of theballoon inflation. This damage may include dissection, elevation ofplaque, disruption of tissue, irregularity of surface.

The plaque tack delivery catheter is loaded with multiple tacks that maybe placed at the discretion of the operator, and advanced over aguidewire in the blood vessel to the location where the dissection ordisruption or irregularity has occurred. The location is specificallyand carefully identified using angiography. The plaque tack(s) is or aredeployed at the location(s) of the lesion. More than one tack may beplaced to tack down a major dissection. If more than one tack is placed,it may be placed only according to the rules of proper spacing of tacks.That is, the tack should be at least one tack axial length apart. Afterplacement of the tack, it may be further expanded into the wall of theblood vessel using a standard angioplasty balloon or a drug-eluting ordrug coated balloon (either as a stand alone (separate) device orintegral to the delivery system). The purpose of the tack is generallynot to hold the blood vessel lumen open but to tack down the non-smoothor dissected surface of the blood vessel. This “touch-up strategy”permits the resolution of the damage created by the drug-eluting or drugcoated balloon without resorting to stent placement and therebymaintaining a “stent-free” environment.

As a further measure, described above, the plaque tack device itself canbe used to deliver medication to the blood vessel. In addition to thedelivery of medication from the anchors, the tack can be coated withmedication prior to tack placement. The purpose of this activity is topermit the tack to elute biologically active agent or agents that havepositive effects on the blood vessel.

One or more of the tacks deployed in accordance with the presentinvention may be coated with or otherwise carry a drug to be eluted overtime at the deployment site. Any of a variety of therapeutically usefulagents may be used, including but not limited to, for example, agentsfor inhibiting restenosis, inhibiting platelet aggregation, orencouraging endothelialization. Some of the suitable agents may includesmooth muscle cell proliferation inhibitors such as rapamycin,angiopeptin, and monoclonal antibodies capable of blocking smooth musclecell proliferation; anti-inflammatory agents such as dexamethasone,prednisolone, corticosterone, budesonide, estrogen, sulfasalazine,acetyl salicylic acid, and mesalamine, lipoxygenase inhibitors; calciumentry blockers such as verapamil, diltiazem and nifedipine;antineoplastic/antiproliferative/anti-mitotic agents such as paclitaxel,5-fluorouracil, methotrexate, doxorubicin, daunorubicin, cyclosporine,cisplatin, vinblastine, vincristine, colchicine, epothilones,endostatin, angiostatin, Squalamine, and thymidine kinase inhibitors;L-arginine; antimicrobials such astriclosan, cephalosporins,aminoglycosides, and nitorfuirantoin; anesthetic agents such aslidocaine, bupivacaine, and ropivacaine; nitric oxide (NO) donors suchas lisidomine, molsidomine, NO-protein adducts, NO-polysaccharideadducts, polymeric or oligomeric NO adducts or chemical complexes;anti-coagulants such as D-Phe-Pro-Arg chloromethyl ketone, an RGDpeptide-containing compound, heparin, antithrombin compounds, plateletreceptor antagonists, anti-thrombin antibodies, anti-platelet receptorantibodies, enoxaparin, hirudin, Warafin sodium, Dicumarol, aspirin,prostaglandin inhibitors, platelet inhibitors and tick antiplateletfactors; interleukins, interferons, and free radical scavengers;vascular cell growth promoters such as growth factors, growth factorreceptor antagonists, transcriptional activators, and translationalpromotors; vascular cell growth inhibitors such as growth factorinhibitors (e.g., PDGF inhibitor—Trapidil), growth factor receptorantagonists, transcriptional repressors, translational repressors,replication inhibitors, inhibitory antibodies, antibodies directedagainst growth factors, bifunctional molecules consisting of a growthfactor and a cytotoxin, bifunctional molecules consisting of an antibodyand a cytotoxin; Tyrosine kinase inhibitors, chymase inhibitors, e.g.,Tranilast, ACE inhibitors, e.g., Enalapril, MMP inhibitors, (e.g.,Ilomastat, Metastat), GP IIb/IIIa inhibitors (e.g., Intergrilin,abciximab), seratonin antagnonist, and 5-HT uptake inhibitors;cholesterol-lowering agents; vasodilating agents; and agents whichinterfere with endogeneus vascoactive mechanisms. Polynucleotidesequences may also function as anti-restenosis agents, such as p15, p16,p18, p19, p21, p27, p53, p57, Rb, nFkB and E2F decoys, thymidine kinase(“TK”) and combinations thereof and other agents useful for interferingwith cell proliferation. The selection of an active agent can be madetaking into account the desired clinical result and the nature of aparticular patient's condition and contraindications. With or withoutthe inclusion of a drug, any of the tacks disclosed herein can be madefrom a bioabsorbable material. Various polymeric carriers, bindingsystems or other coatings to permit controlled release of active agentfrom the tack or its coating are well known in the coronary stent artsand not reproduced herein.

In summary, the plaque tack can be used for plaque retention followingballoon angioplasty treatment of atherosclerotic occlusive disease whileavoiding problems with the use of stents due to installing a large massof foreign material in the body which may cause injury, inflammation,and/or provide sites for restenosis. In contrast with stents, the plaquetack device minimizes the material structure while only being installedat one or more plaque dissection sites that require retention. The focalelevating elements on the tack periphery minimizes the contact surfacearea of the plaque tack with the blood vessel walls and reduces the riskof causing plaque dissection or injury to the blood vessel walls. Thisapproach offers clinicians the ability to perform a minimally invasivepost-angioplasty treatment and produce a stent-like result without usinga stent.

Although this invention has been disclosed in the context of certainpreferred embodiments and examples, it will be understood by thoseskilled in the art that the present invention extends beyond thespecifically disclosed embodiments to other alternative embodimentsand/or uses of the invention and obvious modifications and equivalentsthereof. In addition, while a number of variations of the invention havebeen shown and described in detail, other modifications, which arewithin the scope of this invention, will be readily apparent to those ofskill in the art based upon this disclosure. It is also contemplatedthat various combinations or sub-combinations of the specific featuresand aspects of the embodiments may be made and still fall within thescope of the invention. Accordingly, it should be understood thatvarious features and aspects of the disclosed embodiments can becombined with or substituted for one another in order to form varyingmodes of the disclosed invention. Thus, it is intended that the scope ofthe present invention herein disclosed should not be limited by theparticular disclosed embodiments described above, but should bedetermined only by a fair reading of the claims that follow.

Similarly, this method of disclosure, is not to be interpreted asreflecting an intention that any claim require more features than areexpressly recited in that claim. Rather, as the following claimsreflect, inventive aspects lie in a combination of fewer than allfeatures of any single foregoing disclosed embodiment. Thus, the claimsfollowing the Detailed Description are hereby expressly incorporatedinto this Detailed Description, with each claim standing on its own as aseparate embodiment.

What is claimed is:
 1. An intravascular implant configured to becompressed for delivery and to self-expand when deployed, the implantcomprising: a self-expanding tubular body having a proximal end, adistal end, and a lumen extending therethrough along a central axis ofthe body, the body comprising a plurality of metal struts; wherein thebody has a compression force curve being a measure of radial forcerequired to compress the body along a range of outer diameters and hasan expansion force curve being a measure of radial force exerted by thebody when the body radially self-expands along the range of outerdiameters, the range of outer diameters being at least 2 mm and adifference between the radial force of the compression force curve andthe radial force of the expansion force curve is no more than 4 Newtons(N) at each diameter through the range of outer diameters.
 2. Theimplant of claim 1, wherein the radial force of the compression forcecurve and the radial force of the expansion force curve is no more than3 N at each diameter through the range of outer diameters.
 3. Theimplant of claim 1, wherein the radial force of the compression forcecurve and the radial force of the expansion force curve is no more than2 N at each diameter through the range of outer diameters.
 4. Theimplant of claim 1, wherein the radial force of the compression forcecurve and the radial force of the expansion force curve is no more than1 N at each diameter through the range of outer diameters.
 5. Theimplant of claim 1, wherein the range of outer diameters is at least 3mm.
 6. The implant of claim 1, wherein the range of outer diameters isat least 4 mm.
 7. The implant of claim 1, wherein the range of outerdiameters is at least 5 mm.
 8. The implant of claim 1, wherein the bodycomprises a bridge comprising an anchor configured to remain within acircular shape formed by the body when the body is in a cylindricalconfiguration and to protrude out of the circular shape when the body isforced out of the cylindrical configuration.
 9. The implant of claim 1,further comprising an anchor configured to remain within a cylinderdefined by the body when the body is in a cylindrical configuration andto extend outwards when the body is forced out of the cylindricalconfiguration.
 10. An intravascular implant configured to be compressedfor delivery and to self-expand when deployed, the implant comprising: aself-expanding tubular body having a proximal end, a distal end, and alumen extending therethrough along a central axis of the body, the bodycomprising a plurality of metal struts; wherein the body has acompression force curve being a measure of radial force required tocompress the body along a range of outer diameters and has an expansionforce curve being a measure of radial force exerted by the body when thebody radially self-expands along the range of outer diameters, a rangeof outer diameters being at least 2 mm and a change in radial forcealong the expansion force curve is no more than 3 Newtons (N) along therange of outer diameters.
 11. The implant of claim 10, wherein theradial force along the expansion force curve changes by no more than 2 Nalong the range of outer diameters.
 12. The implant of claim 10, whereinthe radial force along the expansion force curve changes by no more than1 N along the range of outer diameters.
 13. The implant of claim 10,wherein the range of outer diameters is at least 3 mm.
 14. The implantof claim 10, wherein the range of outer diameters is at least 4 mm. 15.The implant of claim 10, wherein the range of outer diameters is atleast 5 mm.
 16. The implant of claim 10, wherein the body comprises abridge comprising an anchor configured to remain within a circular shapeformed by the body when the body is in a cylindrical configuration andto protrude out of the circular shape when the body is forced out of thecylindrical configuration.
 17. The implant of claim 10, furthercomprising an anchor configured to remain within a cylinder defined bythe body when the body is in a cylindrical configuration and to extendoutwards when the body is forced out of the cylindrical configuration.18. An intravascular implant configured to be compressed for deliveryand to self-expand when deployed, the implant comprising: aself-expanding tubular body having a proximal end, a distal end, and alumen extending therethrough along a central axis of the body, the bodycomprising a plurality of metal struts; wherein the body has acompression force curve being a measure of radial force required tocompress the body along a range of outer diameters and has an expansionforce curve being a measure of radial force exerted by the body when thebody radially self-expands along the range of outer diameters, a rangeof outer diameters being at least 2 mm and the radial force along theexpansion force curve being no more than 5 Newtons (N) along the rangeof outer diameters.
 19. The implant of claim 18, wherein the radialforce along the expansion force curve is no more than 4 N along therange of outer diameters.
 20. The implant of claim 18, wherein theradial force along the expansion force curve is no more than 3 N alongthe range of outer diameters.
 21. The implant of claim 18, wherein theradial force along the expansion force curve is no more than 2 N alongthe range of outer diameters.
 22. The implant of claim 18, wherein theradial force along the expansion force curve is no more than 1 N alongthe range of outer diameters.
 23. The implant of claim 18, wherein therange of outer diameters is at least 3 mm.
 24. The implant of claim 18,wherein the range of outer diameters is at least 4 mm.
 25. The implantof claim 18, wherein the range of outer diameters is at least 5 mm. 26.The implant of claim 18, wherein the body comprises a bridge comprisingan anchor configured to remain within a circular shape formed by thebody when the body is in a cylindrical configuration and to protrude outof the circular shape when the body is forced out of the cylindricalconfiguration.
 27. The implant of claim 18, further comprising an anchorconfigured to remain within a cylinder defined by the body when the bodyis in a cylindrical configuration and to extend outwards when the bodyis forced out of the cylindrical configuration.